The ATP has announced an internal investigation is currently underway into allegations concerning Alexander Zverev at the ATP Masters event in Shanghai in 2019.
Earlier this year, the ATP commissioned an Independent Safeguarding Report, a review to ensure all adults and minors involved in professional tennis are safe and protected from abuse.
In a statement, the ATP said it "fully condemns any form of violence or abuse" and "will investigate such allegations related to conduct at an ATP member tournament".
ATP CEO Massimo Calvelli said: "The allegations raised against Alexander Zverev are serious and we have a responsibility to address them.
"We hope our investigation will allow us to establish the facts and determine appropriate follow-up action.
"We understand Zverev welcomes our investigation and acknowledge that he has denied all allegations.
"We will also be monitoring any further legal developments following the preliminary injunction obtained by Zverev in the German Courts."
An Independent Safeguarding Report, commissioned by the ATP earlier in the season, has been completed. It represents a key element of the ATP’s overall safeguarding review to ensure all adults and minors involved in professional tennis are safe and protected from abuse.
— ATP Tour (@atptour) October 4, 2021
Zverev's former partner Olga Sharypova has accused him of physical and emotional abuse and revealed to journalist Ben Rothenburg that emotional abuse turned physical the week before the 2019 US Open.
She said that Zverev’s controlling and possessive behavior had first turned physically violent months earlier, but in New York that violence reached a new level.
"I was screaming, and because of that he threw me down onto the bed, took a pillow, and then sat on my face," she said.
"I couldn’t breathe for some time, and I’m just trying to get out of it. I’m screaming and started to run."
Sharypova then travelled to the Laver Cup in Geneva with Zverev in September of that year, where she said he punched her in the face.
"In that fight he punched me in the face for the first time.
"In other fights he was pushing me, shoving me, twisting my arms, choking me. But this was the first time he punched me, really punched me."
In a second interview with Rothenburg, she described additional physical and emotional abuse in Shanghai, in October 2019.
Zverev denied the allegations, describing them as "unfounded" and "simply not true".
The Independent Safeguarding Report was compiled by a team of experts led by Chris Smart, former Detective Chief Inspector in the Metropolitan Police (UK).
The report outlines a number of wide-ranging recommendations to ensure safeguarding is embedded across all aspects of ATP organisational activity.
Topics covered include prevention, reporting and investigation of abuse, disciplinary measures, policy statements, event safety, training, information sharing, collaboration with other bodies of tennis and the appointment of dedicated safeguarding leads.
"My feeling is still that, you know, the tour…needs to…be more proactive in dealing with situations like that, or allegations like that, because… The way that it’s [been] handled hasn’t been good for anyone," Murray said.
"I don’t think it’s been great for the tour. I don’t think it’s been great for Zverev, because you know, unless it gets addressed head-on, it’s just going to be lingering, and, like you say, the questions will continue to be getting asked.
"Like, I spoke about it at Wimbledon, and now here, what is it, three months later, and I’m still getting asked about it.
"So, obviously, it’s not been properly addressed, and until that happens, then players are going to continue to get asked about it.
"The broadcasters are invariably going to be talking about it. So… I don’t know what advice Zverev will be getting… and I don’t know how you should handle that if you are in that situation or in that position.
"It’s difficult, but, certainly, it’s been going on too long… It needs to get resolved, clearly."