The coach of Sloane Stephens has accused Victoria Azarenka of "cheating within the rules" during the world No.1's controversial semi-final win at the Australian Open.
Azarenka has been criticised for unsportsmanlike behaviour during her victory over Stephens for calling a medical time out at a crucial juncture in the match.
Critics claim Azarenka wasn't injured and she called for the 10 minute break to regain her composure after failing to serve out the match.
Stephens's coach David Nainkin said Azarenka acted against the spirit of tennis.
"I thought it was very unfair - cheating within the rules," Nainkin told USA Today.
"It was unsportsmanlike. I don't think you should be able to leave the court before the opponent serves for 10 minutes for whatever reason.
"You'd better have something pretty good. I think there's a grey area in the rule book that shouldn't be allowed. End of story."
Attempting to serve out the match at 5-3 in the second set, Azarenka blew five match points before losing her serve and calling a time out.
After a delay of 10 minutes, the Belarusian returned to the court and broke Stephens's serve to win 6-1 6-4.
In an on-court interview after the match, Azarenka said she had avoided "the choke of the year" and "felt a bit overwhelmed" after dropping her serve, prompting allegations that she called the time out despite not being injured.
She later changed her story and maintained that she had received treatment for a back injury.
"It was a necessary thing for me to do," she said.
"I just regret that I didn't take it earlier, that it got to the point that it was pretty much impossible for me to breathe and to play."
Azarenka said she had misunderstood the question when asked about her time out immediately after the match.
Azarenka's initial response led to calls of gamesmanship from respected commentator Pam Shriver, while fellow ESPN commentator Patrick McEnroe labelled it an "absolute travesty".
Australian Open tournament director Craig Tiley said on evidence from the doctor who treated Azarenka and the trainer who treated her, everything was above board.
"Certainly when these things happen and the trainers are called to the court the referee and myself we have a conversation," Tiley told 7 Sport.
"In this instance the doctor confirmed he did treat the rib, he did treat the knee and once he made that assessment she was able and ready to continue play."
For her part, 19-year-old Stephens refused to criticise Azarenka.
"If it was one of my friends I would say, 'Oh my god that sounds like a PP,' which is a personal problem," Stephens said.
"I love Vika and we share the same agent. We actually are pretty good friends. I'm sure I will see her and we'll talk about it.
"I hope she wins the final, so I hope if that's the case she should figure it out, something, get it together."