Nick Kyrgios has used social media to bite back at a sledge from the mother of tennis rival Stefanos Tsitsipas.
Tension has been building with the Kyrgios and Tsitsipas camps since the controversial match at Wimbledon earlier this year when the Australian triumphed.
During the heated blockbuster, Kyrgios asked the chair umpire to default Tsitsipas after the Greek star smashed a shot into crowd, and then refused to play until chatting to the tournament supervisor.
In response, Tsitsipas purposefully belted a shot directly at Kyrgios in play as the Australian approached the net.
Now months later, Tsitsipas' mother Julia Apostoli took a swipe at Kyrgios, accusing him of playing 'dirty tennis' in the match against her son.
"The only person who confuses Stefanos is Nick Kyrgios," Apostoli told the Greek City Times last week.
"He is the only one who brings him out of himself.
"In the Wimbledon match, Kyrgios decided to ignore the general rules of sports. The match became very strange and nervous because he was playing ‘dirty’ tennis.
"Stefanos doesn’t play like that. He completely lost his temper due to the behaviour of his opponent and lost the match without being any worse on the court."
Kyrgios finally responded to Apostoli's accusation by posting a video on his Instagram stories of executing a clean drop shot against Tsitsipas.
He captioned the post, "dirty tennis".
Since his US Open semi-final loss to Karen Khachanov, Kyrgios has only played in the Japan Open earlier this month, where he withdrew through a left knee injury prior to his quarter-final against Taylor Fritz.
ATP tournaments in Basel or Paris later this month have been touted as potential return targets for Kyrgios.
"I've been playing amazing tennis all year and actually was dealing with a bit of a knee issue around the US Open time," Kyrgios said after withdrawing from the Fritz match.
"I got back home and probably didn't take enough time off, to be honest. I went straight back into training."
"But pulling out is the smart option for my body. I've got a couple of events left in the year and I want to do well in them, so I have to be smart."