“Players need to speak out,” Wawrinka wrote on Twitter on Tuesday. “Justin Gimelstob has been convicted of a violent assault. It simply cannot be possible for anyone to condone this type of behavior and worse, support it. In any other business or sport we would not be discussing this. The council @ATP_Tour need to do something about this and finally end this conversation and shameful period in our great sport.”

As recently as Monday, Gimelstob’s lawyer sent a letter to members of the player council and the board seeking to clarify the legal terms of the case and mitigate the damage in public opinion.

But by the time of Wawrinka’s tweet, Gimelstob said, he was on his way from Los Angeles to Spain to discuss his resignation with Novak Djokovic in person. Djokovic, the world No. 1 and president of the ATP Player Council, was preparing there for next week’s Madrid Open.

He has become one of Gimelstob’s leading allies in tennis, and while Gimelstob was facing a criminal charge, they worked closely together to defeat Chris Kermode in March in his unsuccessful attempt to extend his contract as the ATP’s executive chairman and president. The ATP Player Council was deeply divided on that issue, which was ultimately decided by a vote of the board.

“I wanted to look Novak in the eye, and the two most important things I wanted to say were first thank you and second to apologize,” Gimelstob said.

Gimelstob has been the representative for the Americas on the ATP board since 2008. He is one of three representatives elected by the player council. The tournaments also have three representatives on the board, and there is often internal tension between those groups as the players seek greater influence, prize money and benefits, and the tournaments seek to control costs and the calendar.

Gimelstob has been considered a fierce advocate for the players as they secured significant prize money increases from the four Grand Slam tournaments and the tour’s other top-tier events. Though Gimelstob’s highest ranking as a singles player was No. 63 in 1999, he rose to become one of the most influential figures in the sport as an executive, an on-air analyst for Tennis Channel and a coach and adviser to John Isner, the top 10 player from the United States.