Foul-mouthed Greek Stefanos Tsitsipas has apologised after branding a linesman a "malaka" during his explosive third-round Australian Open win over Georgia's Nikoloz Basilashvili.
The 14th seed was furious that the line judge's error cost him a chance to wrap up the third set while up 5-3 on Margaret Court Arena on Friday.
"That wanker has f***ed me, f*** your house," Tsitsipas yelled towards the linesman in his native Greek tongue.
The outburst resulted in a code violation and a fine is certain to follow.
"It was the heat of the moment, I said some really bad things," the 20-year-old said after the match.
"I regret saying them but I really wanted this really bad.
"At that moment it felt like it was slipping out, you know, Basilashvili kind of found comfort and confidence after that. So I was really frustrated.
"I wish I could change that, I wouldn't say that."
Tsitsipas recovered from the mid-match meltdown, triumphing 6-3 3-6 7-6 (9-7) 6-4 over the 19th-seeded Georgian in two hours and 54 minutes.
He's also earned his place in the history books as the first Greek man to reach the round of 16 at two tennis majors.
On Sunday he will face defending champion Roger Federer - a 6-2 7-5 6-2 winner over American Taylor Fritz.
The duo last met at the Hopman Cup in Perth, where the Swiss world No.3 prevailed 7-6 (7-5) 7-6 (7-4).
"I learnt a lot since my last match with him," Tsitsipas said.
"I know the patterns that he's using a bit better now and he's serving really well, so I'm going to have to utilise this and take advantage of my returns as much as possible.
"He's a legend of our sport, it will be a great day facing him in one of the best arenas, Rod Laver. I'm really excited."
Also through to the third round is Tomas Berdych after the Czech's 5-7 6-3 7-5 6-4 win over 18th-seed Argentinian Diego Schwartzman.
Bulgaria's former semi-finalist Grigor Dimitrov beat Italy's Thomas Fabbiano 7-6 (7-5) 6-4 6-4.
Australian Associated Press