MONTREAL — 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.

That’s the maximum allowed by the ATP rulebook for incidents of verbal abuse or unsportsmanlike conduct. The ATP said it’s still reviewing the matter and additional penalties could apply.

On Wednesday night, a courtside microphone picked up Kyrgios saying fellow Australian player Thanasi Kokkinakis had slept with a player who reportedly is Wawrinka’s girlfriend.

Wawrinka tweeted early Thursday morning: “There is no need for this kind of behaviour on or off the court and I hope the governing body of this sport does not stand for this.” He called the 20-year-old 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.”

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 since has been linked with 19-year-old Donna Vekic, who is ranked 127th.

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.”

Thumbnail photo via Jean-Yves Ahern/USA TODAY Sports Images