NXGN: Mbappe, Pulisic, Donnarumma and 2017's best wonderkids

THEN: Having made his senior debut as a 16-year-old, Lainez was regarded as the best prospect in Mexican football as he bore a passing resemblance to Lionel Messi in his style of play.

NOW: Lainez joined Real Betis in a deal worth €12 million (£11m/$14m) in January 2019, making him the second-most expensive Mexican bought by a European club. Quickly became the youngest Mexican to score in the Europa League, but has struggled to truly establish himself in La Liga.

THEN: Nicknamed 'The Japanese Messi', Kubo was forced to return to his homeland in the aftermath of Barcelona's FIFA-imposed transfer ban having been invited to La Masia as a 10-year-old.

NOW: After breaking a swathe of J-League records, Kubo returned to Spain in the summer of 2019 as he was snapped up by Real Madrid. Impressed on loan at Mallorca last season but saw his spell with Villarreal in 2020 cut short. Currently earning more experience at Getafe.

THEN: Impressive in the Blues' youth ranks, right-back Sterling was being tipped to make the leap into Antonio Conte's first-team squad.

NOW: Sterling made his senior debut in the autumn of 2017 but has only represented Chelsea on one further occasion. Had loan spells with Coventry City and Wigan Athletic and is currently playing for Chelsea's Under-23s side.

THEN: Likened to Toni Kroos by those in the know around the Bundesliga champions, Dorsch was being closely monitored by Bayern boss Carlo Ancelotti.

NOW: Despite scoring on his Bundesliga debut, Dorsch was released by Bayern in 2018 and joined second division side FC Heidenheim on a free transfer. He subsequently moved to Gent in the summer of 2020 for a fee of €3.5m (£3m/$4.2m).

THEN: Winner of the Golden Ball as Nigeria won the 2015 Under-17 World Cup, Nwakali joined Arsenal a year later. Sent out on loan to Dutch lower league side Maastricht to earn first-team experience.

NOW: Nwakali returned to the Netherlands in 2017 for loan spells with VVV-Venlo and Maastricht before spending time with Porto's 'B' team. Eventually left Arsenal on a permanent basis to join Huesca, having never made an appearance at senior level for the Gunners. Made his La Liga debut in September 2020, and is currently on loan with Spanish second division side Alcorcon.

THEN: Became the joint-youngest player to debut in Serie A at the age of 15 years and 280 days. A playmaking forward, Pellegri had already turned down an offer to move to Manchester United.

NOW: Joined Monaco in January 2018 in a deal worth €25m (£22m/$31m), making him the second-most expensive 16-year-old in history. Serious injuries have stalled his career, however, with the youngster having made only a handful of Ligue 1 appearances thus far.

THEN: The youngest player and scorer in Partizan history, Vlahovic was handed a first professional contract at the age of 15, such was the young striker's promise. Linked with a move to Fiorentina.

NOW: Vlahovic did indeed join Fiorentina in January 2018 and has emerged as one of the leaders of their attack over the past 18 months.

THEN: Described as having the characteristics "of a young Messi" by Spurs boss Mauricio Pochettino, winger Edwards had already made his first-team debut for the north London outfit.

NOW: Cut short a loan spell at Norwich City in 2018 before spending a year in Eredivisie with Excelsior. Joined Vitoria on a permanent basis in the summer of 2019 and has impressed during his two seasons in Portugal, leading to reports linking him with a move back to the Premier League.

THEN: Named as player of the tournament at the Under-17s European Championship in 2016, striker Gomes became the youngest player to represent Benfica in continental competition when coming off the bench against Napoli in the Champions League.

NOW: A regular in Benfica's 'B' team, Gomes spent the 2019-20 season on loan at Portimonense and Lechia Gdansk. Joined Bulgarian outfit Cherno More on a permanent basis in February 2021.

THEN: An out-and-out striker, Pinamonti made his Inter debut in December 2016 in their Champions League win over Sparta Prague before making his Serie A bow two months later.

NOW: Having spent the 2018-19 season out on loan at Frosinone, he joined Genoa in June 2019 on loan with an obligation to buy, and scored seven goals in all competitions. Inter re-signed him in the summer of 2020, but he has made only brief appearances for Antonio Conte's side.

THEN: A regular in Madrid's Castilla side and already a full Morocco international, Hakimi had earned call-ups to Zinedine Zidane's squad but had yet to make his first-team debut for the Blancos.

NOW: Made sporadic appearances for Madrid in 2017-18 before joining Borussia Dortmund on a two-year loan deal. Having impressed at Signal Iduna Park, Inter forked out €40m (£36m/$45m) in the summer of 2020 to take him to San Siro and been rewarded with a string of sensational performances during their Scudetto charge.

THEN: Already regarded as one of the best players in City's academy, Brahim was a favourite of Pep Guardiola and made his first-team debut in September 2016.

NOW: As he struggled for regular first-team minutes at City, the Spanish playmaker joined Real Madrid in a deal worth an initial €17m (£15m/$19m) in January 2019. Currently on loan at AC Milan, where he is enjoying his most consistent run of senior appearances to date.

THEN: The top scorer as Brazil won the Under-17s South American Championships in 2015, Leandrinho swapped Ponte Preta in his homeland to join Napoli in January 2017.

NOW: The forward never played a game for the Serie A outfit, and instead spent time out on loan at Atletico Mineiro and Red Bull Bragantino before joining the latter on a permanent basis in the summer of 2020.

THEN: Likened to Ronaldinho for his ability with the ball at his feet, England Under-17 captain Gomes was regarded as the brightest prospect in the United academy structure for some time.

NOW: Skippered England to the Under-17 World Cup title in 2017 having already become the first player born in the 2000s to appear in the Premier League. Failed to hold down a first-team berth, however, and joined Lille on a free transfer in 2020 before heading out on loan to Boavista for the current campaign.

THEN: Tipped as the forward to follow in the footsteps of Luis Suarez and Edinson Cavani, Ardaiz scored twice as Uruguay beat Ecuador to win the South American Under-20 Championship in early 2017.

NOW: Ardaiz has struggled to live up to the hype. Spent time on loan at Royal Antwerp before making a permanent move to Swiss side Chiasso. Endured further unsuccessful loan spells at Frosinone and Vancouver Whitecaps before joining Lugano in the summer of 2020.

THEN: Hot on the heels of Andre Silva emerging from Porto's famed academy, Pedro made headlines when scoring an injury-time winner against Braga on his first-team debut in December 2016.

NOW: That goal is the high point of Pedro's career to date. After four loan spells, he joined second division side Leixoes in 2020 before moving on to another Liga Portugal outfit, Penafiel, in January of this year.

THEN: The son of Romania legend Gheorge, the young Hagi possessed the same ability when on the ball. Joined Fiorentina in the summer of 2016 having impressed for Viitorul Constanța in his homeland.

NOW: Hagi returned to Viitorul, where he scored 20 goals in 53 appearances before leaving for Genk in the summer of 2019. Joined Rangers on loan six months later before making the move to Ibrox permanent ahead of their title-winning 2020-21 campaign.

THEN: Handed his first-team debut by Luiz Felipe Scolari as a 16-year-old, the attacking midfielder captained Brazil at the Under-17 World Cup in 2015.

NOW: Spent time on loan at Caykur Rizespor and America Mineiro before joining Portuguese club Santa Clara in 2019.

THEN: The youngest player selected by any country at the 2017 African Cup of Nations, the Senegalese winger came through the same academy as his hero Sadio Mane.

NOW: Despite interest from Barcelona, joined Rennes in the summer of 2017. Enjoyed a breakthrough campaign in 2018-19 which earned him a €35m (£32m/$39m) move to Watford, where his initial displays saw him linked with a move to Liverpool.

THEN: Having joined La Masia at the age of seven, Alena – who was likened to Deco and Andres Iniesta – marked his first-team debut for the Blaugrana with a goal against Hercules in the Copa del Rey.

NOW: Alena has made sporadic appearances for the Barca senior side without ever holding down any kind of regular place. Currently on loan at Getafe having previously spent time at Real Betis.

THEN: Though the playmaker was invited to have a trial with Liverpool before joining San Lorenzo in 2014, Conechny's biggest contribution to the game at this stage of his career was missing the final of the South American Under-17s Championship in 2015 having fallen out of a window while playing FIFA on the Playstation!

NOW: Having made a handful of appearances for San Lorenzo, the Argentine joined Portland Timbers on loan in 2018 before eventually making the move permanent a year later, despite not always being an automatic starter.

THEN: Already a regular in the Ajax first team at the age of 17. The second-youngest goalscorer in the club's history behind Clarence Seedorf after netting on his debut in September 2016.

NOW: Having become the youngest player to appear in a major European final in the 2017 Europa League, De Ligt shone as Ajax won a domestic double and reached the Champions League semi-finals two years later, with his performances earning him the Kopa Trophee at the Ballon d'Or ceremony. Joined Juventus in a €75m (£68m/$84m) deal in the summer of 2019 and, after a shaky start, is now a key figure in Turin.

THEN: Comfortable across the forward line, Schiapasse left River Plate Montevideo for Atletico Madrid in the summer of 2016, and was thought to be on verge of making his debut for Diego Simeone's side.

NOW: That first-team debut at Atleti never came, and after three underwhelming loan spells, he joined Sassuolo in October 2020. Recently returned to Uruguay by signing on loan at Penarol for the remainder of 2021.

THEN: Having come through the PSG ranks, Callegari made his first-team debut in November 2016 and was being tipped to become a regular in the first-team squad in the months to come.

NOW: Callegari never did make another appearance for PSG and left for Genoa in the summer of 2018. Spent time on loan at third-tier side Ternana before returning to France to first join Avranches before switching to Ligue 2 side Chambly in the summer of 2020.

THEN: One of the revelations of the 2016-17 Ligue 1 season, Cote d'Ivoire-born Karamoh showcased his ability as both a wide forward and a central striker.

NOW: The attacker joined Inter in the summer of 2017 but made little impact before loan spells at Bordeaux and Parma, the latter of whom he joined permanently ahead of the 2020-21 campaign.

THEN: Having made his PSG debut at the start of the 2016-17 campaign, Ikone was sent out on loan to Montpellier in January 2017 to earn further first-team experience.

NOW: After 18 months at Montpellier, Ikone made a permanent switch to Lille in the summer of 2018, where he remains a key figure. Earned a first France call-up in 2019 before scoring on his international debut against Albania.

THEN: Having made his senior debut as a 17-year-old, attacking midfielder Barco was being linked with a summer move to Benfica.

NOW: Scored in the final of the 2017 Copa Sudamerica before joining Atlanta United in a deal worth a reported $15m (£11m) in January 2018. Was named in the MLS All-Star team in each of his first two campaigns in the U.S.

THEN: Having captained Liverpool at various age-group levels, the full-back was making his first steps into senior football, earning strong reviews from Jurgen Klopp and Steven Gerrard.

NOW: Regarded by many as one of the world's top right-backs, the England international is already an English, European and World champion and the youngest player to start successive Champions League finals.

THEN: The winner of the 2016 Titi d'Or (the prize awarded to the best player in PSG's academy), the winger was being linked with moves to Manchester City and Juventus as he waited to make his senior debut.

NOW: Diaby eventually made his first-team bow while on loan at Crotone before returning to Paris, where he made sporadic appearances ahead of signing for Bayer Leverkusen on a permanent deal in the summer of 2019.

THEN: The son of Barcelona and Netherlands legend Patrick, the young Kluivert had recently broken into the Ajax first team as a wide forward.

NOW: After establishing himself in the Ajax team and winning the 2018 NXGN award, Kluivert joined Roma in the summer of 2018 in a deal worth €18.75m (£16.5m/$22m). Despite some encouraging performances initially, he soon found himself out of favour, and joined RB Leipzig on loan for the current campaign.

THEN: Made headlines as he became the youngest player to score in Liverpool history at the age of just 17 years and 45 days, taking the record off Michael Owen with his goal against Leeds.

NOW: Scored a stunning winning goal on his Wales debut in September 2017, but Woodburn's career has since stalled somewhat. Spent time out on loan at Sheffield United, Oxford United and Blackpool and is currently back representing Liverpool's Under-23s.

THEN: The first player born in the 2000s to appear in the Champions League, excitement was building around 17-year-old Kean, with the Bianconeri believing they had a world-class talent on their hands.

NOW: After a loan spell at Verona, he returned to Juve in 2018 and began to make an impact towards the end of the 2018-19 campaign, while also becoming the youngest Italy goalscorer ever. Joined Everton in 2019 in a €27.5m (£25m/$31m) deal but struggled for the Toffees. Currently resurrecting his reputation on loan at PSG.

THEN: Regarded as the best player ever to come out of Luxembourg despite being just 17, Thill became the first player born in the 2000s to debut in one of Europe's top five leagues in September 2016. Linked with moves to Bayern Munich and Real Madrid.

NOW: A veteran of 29 caps for his country, Thill joined Portuguese side Nacional in the summer of 2020 after loan spells with French lower league outfits Pau and Orleans.

THEN: The youngest player in West Ham history, Oxford made headlines on his Premier League debut as the 16-year-old defender shone in a 2-0 win over Arsenal at the Emirates Stadium. Loaned out to Reading for the 2016-17 season despite Manchester City and Arsenal showing an interest in signing him.

NOW: Spent further time out on loan at Borussia Monchengladbach (twice) and Augsburg before joining the latter on a permanent deal in the summer of 2019.

THEN: Having been likened to Sergio Aguero as he came through the ranks in his native Paraguay, Madrid won the race to sign Diaz ahead of Liverpool and Manchester United after a series of eye-catching performances during his first steps into senior football.

NOW: Yet to make a first-team appearance for the Blancos despite recently turning 23. Currently on loan in Liga MX with Club America after previous stints with Lugo, Corinthians and boyhood club Cerro Porteno.

THEN: The first player born in the 2000s to score an English league goal and the youngest to ever score in a Championship game, left-back turned winger Sessegnon was being compared to Gareth Bale by onlookers.

NOW: After helping Fulham earn promotion to the Premier League in 2018, he joined Tottenham for £25m ($30m) a year later, but has struggled to make an impact in north London thus far. Currently impressing on loan at Hoffenheim, though.

THEN: The youngest Bundesliga debutant in Leverkusen history, Havertz was turning heads around Europe, with some comparing the teenage creative midfielder to Mesut Ozil.

NOW: An established Germany international, Havertz transferred to Chelsea in the summer of 2020 for £70m ($91m) and despite making a slow start to life at Stamford Bridge, he is beginning to show what all the fuss was about.

THEN: Captain of the England Under-19s, midfielder Davies began to make himself a regular in the Everton first team in early 2017, with his superb goal against Manchester City an early highlight.

NOW: The Merseyside native remains a key squad member at Goodison Park, though he has not always been a regular starter for the Toffees.

THEN: Having earned rave reviews at Dinamo Zagreb, Wolfsburg beat Inter to the signing of winger Brekalo before sending him on loan to Stuttgart in January 2017.

NOW: Brekalo impressed during 18 months at Stuttgart before returning to Wolfsburg, where he has become a regular starter over the past two seasons. Also a full Croatia international with 19 caps to his name.

THEN: Having been plucked from the Valenciennes academy by the Red Bull group, the centre-back spent time at Salzburg before moving to RB Leipzig, despite interest from both Barcelona and Juventus.

NOW: Upamecano has grown into one of Bundesliga's best defenders over the past 18 months, with Bayern Munich having beaten off competition from a number of top European clubs by snapping him up for €42.5m (£37m/$51m) from the 2021-22 season on.

THEN: After coming through the famed Ajax academy, versatile defender Fosu-Mensah enjoyed a run of games during the second half of the 2015-16 season under Louis van Gaal. Jose Mourinho's arrival slowed his development somewhat, but he did sign a new contract in October 2016.

NOW: The Netherlands international spent time out on loan at Crystal Palace and Fulham before joining Bayer Leverkusen in January 2021 in a cut-price deal. Currently recovering from an anterior cruciate ligament injury suffered in early-March.

THEN: Became the youngest player and goalscorer in the Norwegian top flight, as well as the youngest player to ever represent Norway before his 16th birthday, and Madrid beat off a host of Europe's biggest clubs to sign Odegaard in January 2015. He played predominantly for the Castilla team before being sent out on loan to Heerenveen to gain further experience.

NOW: Returned to Eredivisie the following year with Vitesse before impressing during the first season of a two-year loan deal at Real Sociedad. Zinedine Zidane recalled him from San Sebastian a year early, but a lack of opportunities saw him join Arsenal on loan in January.

THEN: Likened to Philipp Lahm for his versatility, Passlack broke into the Dortmund first team towards the end of the 2015-16 season and was being used regularly by coach Thomas Tuchel.

NOW: Passlack fell out of favour at Dortmund towards the end of 2017 and spent time out on loan at Hoffenheim, Norwich City and Fortuna Sittard. Back with BVB this season and has made sporadic appearances for the Bundesliga giants.

THEN: Having reportedly attracted interest from Barcelona, Arsenal and AC Milan, the centre-back had drawn comparisons with Samuel Umtiti due to his physique and ball-playing ability.

NOW: Made over 100 appearances for Nice before joining Chelsea on a free transfer in the summer of 2020. Currently on loan at Porto.

THEN: Likened to Andrea Pirlo by some high-profile onlookers, Locatelli had shown enough to suggest he could be a mainstay of the Milan midfield for years to come.

NOW: After slowly falling out of favour, Locatelli handed in a transfer request in 2018 before leaving for Sassuolo on loan. Made the move permanent a year later and his commanding performances in Emilia-Romagna having reportedly caught the attention of Manchester City and Juventus.

THEN: The youngest goalscorer in Swedish national team history, Dortmund beat Real Madrid to the signing of a player who had always had to deal with comparisons to compatriot Zlatan Ibrahimovic.

NOW: Isak struggled to make an impact in the Bundesliga, but after a productive loan spell at Willem II in early-2019, he joined Real Sociedad, where he has found his feet to become one of La Liga's most feared No.9s.

THEN: Tipped as a future France No.1 after becoming the youngest goalkeeper in Ligue 1 history when he made his Toulouse debut as a 16-year-old.

NOW: Currently in the second season of a two-year loan at Nantes, having lost his place as a starter at Fiorentina, whom he joined in the summer of 2018. Still to make a senior appearance for his country.

THEN: The youngest goalscorer in U.S. men's national team history, Pulisic was earning rave reviews having broken into the Dortmund first team at the start of 2016.

NOW: The undisputed face of the USMNT, Pulisic slipped a little down the pecking order at BVB ahead of completing a £58m ($73m) move to Chelsea in 2019. Has endured an up-and-down time in the Premier League, with injuries having limited his game time in west London.

THEN: The youngest player in Monaco history (breaking a record previously held by Thierry Henry), Mbappe was becoming a household name in the early months of 2017 after some scintillating performances in the Champions League while having also become the youngest scorer of a Ligue 1 hat-trick .

NOW: After helping Monaco to the Ligue 1 title and the Champions League semi-finals in 2017, Mbappe joined Paris Saint-Germain on an initial loan deal before becoming the second-most expensive player of all time when signing for the French giants for €180m (£166m/$214m). Already among the top 10 goalscorers in PSG history and a scorer in France's World Cup final victory over Croatia in 2018, he now seems set to challenge for the Ballon d'Or on a yearly basis.

THEN: A true revelation, Donnarumma broke into the AC Milan line-up as a 16-year-old and showed enough quality in his first 18 months in the senior side to mark himself out as the rightful heir to Gianluigi Buffon's starting spot in the Italy team.

NOW: Despite persistent reports linking him with a move away from San Siro, Donnarumma remains one of the Rossoneri's most consistent performers having racked up over 200 Serie A appearances for the club. As expected, he's now the undisputed No.1 at international level for Roberto Mancini's Azzurri.