The ATP fined Nick Kyrgios $10,000 on Thursday for his "insulting comment" toward French Open champion Stan Wawrinka during a match at the Rogers Cup.
On Wednesday, a courtside microphone picked up Kyrgios saying that fellow Australian player Thanasi Kokkinakis had slept with a player who is reportedly now Wawrinka's girlfriend.
The $10,000 is the maximum fine allowed by the ATP rule book for incidents of verbal abuse or unsportsmanlike conduct. Also, the ATP fined Kyrgios an additional $2,500 for unsportsmanlike conduct related to a comment made to a ball person during the match. The tour said Kyrgios has been served with a "Notice of Investigation," which begins a process to determine if his actions also constitute a violation of the "Player Major Offense" provisions set forth under "Aggravated Behavior" or "Conduct Contrary to the Integrity of the Game."
On Friday, Tennis Australia said in a statement that it noted Kyrgios "has apologized to all involved for his comments on court in Montreal yesterday and deeply regrets his actions ... Tennis Australia is working closely with Nick and his team to provide the best possible support; we understand how important it is to help educate and influence him both on and off the court."
Kyrgios' troubles also continued on the court Thursday, when he was beaten 7-5, 6-3 by John Isner, and got into a verbal altercation with a fan.
Wawrinka tweeted Thursday:
He called the 20-year-old's Australian's words "not only unacceptable but also beyond belief."
Kyrgios issued an apology Thursday on his Facebook page.
"My comments were made in the heat of the moment and were unacceptable on many levels," Kyrgios wrote. "I take full responsibility for my actions and regret what happened."
The 30-year-old Wawrinka, ranked fifth in the world, announced in April that he had separated from his wife, with whom he has a daughter. The Swiss player has since been linked with 19-year-old Donna Vekic of Croatia, who is ranked 127th.
Vekic played mixed doubles with Kokkinakis, also 19 and ranked No. 76, at the 2014 Australian Open as a wild-card entry.
Kyrgios beat Wawrinka on Wednesday when the Swiss player retired with a lower-back injury while trailing 4-0 in the third set.
In a post-match interview on court, Kyrgios said Wawrinka had provoked him.
"He was getting a bit lippy at me so, I don't know, it's just in-the-moment sort of stuff," Kyrgios said. "I don't really know, I just said it."
Wawrinka's coach, Magnus Norman, also criticized Kyrgios, who has been at the center of controversy in recent weeks.
"That was really really low Nick Kyrgios," Norman wrote on Twitter. "Hope for u that u have people around that will teach u a thing or 2 about life tonight. Very bad."
At Wimbledon last month, Kyrgios was booed by spectators in a fourth-round loss to Richard Gasquet of France. Kyrgios appeared to make little attempt to return Gasquet's serve during the third game of the second set after a dispute with the chair umpire.
That incident prompted Australian swimming great Dawn Fraser to question the character of Kyrgios and suggest he could leave the country and return to where his parents came from.
Kyrgios, who was born in Australia to a father born in Greece and mother born in Malaysia, replied on Twitter that Fraser was a "blatant racist." She later apologized.