Novak Djokovic expresses support for idea of tennis domestic violence policy

He strongly denies the allegations, which were made by the former junior player on Instagram and in two media interviews, but has not addressed them in any detail.

The ATP had been criticised for not making any public comment until last week, when it issued a generic statement saying it "fully condemns any form of violence or abuse".

Zverev is not the only tennis player to have faced similar allegations recently, with Georgian Nikoloz Basilashvili in court last month to answer an assault charge against his ex-wife.

Several major American sports have a policy setting out a procedure to be followed in such situations, and Djokovic believes tennis should go down the same route.

He said: "I've known Sascha (Zverev) for a very long time since he was very young. I always had a great relationship with him, he's a very nice guy, I have a lot of respect for him, his family. I was sad to hear that he's going through something like this.

"I don't know what happened. Obviously I'm not supporting any kind of violence. Whether ATP should develop a policy? Yes, why not. Probably it should be there in place."

Tennis has largely closed ranks around Zverev, with Australian Daria Gavrilova a notable exception in saying she believes Sharypova, and Djokovic has offered the German his support.

"He's been handling it well by the looks of his results in the last month and a half or so, he's been doing well considering he's got a lot on his plate off the court," said the world number one.

"I sincerely wish for him that he overcomes this soon and that he can focus on his life and tennis career."

Zverev again implied he would not be taking legal action – something Sharypova has also said – and, despite the allegations and the coronavirus pandemic, declared it had been a "great year".

The 23-year-old said: "Unfortunately I lost a lot of big matches. I lost semi-finals in Australia, which I could have won. Lost the final of the US Open, which I should have won. Finals in Bercy (the Paris Masters). This match here.

"The US Open match obviously still hurts, but all the other ones, it's great that I'm playing at this level again."

Djokovic's victory means the four top seeds have all reached the semi-finals for only the second time since 1990, with Rafael Nadal taking on Daniil Medvedev in the other last-four clash at London's O2 arena.

Djokovic, who is chasing a record-equalling sixth title, still was not at his best but played, and fought, a lot better than in his convincing loss to Medvedev on Wednesday.

He won the first seven points of the match and then withstood everything Zverev threw at him in the second set before playing a near-flawless tie-break.

Djokovic has beaten Thiem in seven of their 11 meetings but the Austrian came out on top in London last year and in the French Open semi-finals before Djokovic gained revenge in a five-set Australian Open final.

"I have lots of respect for Dominic, his game, his work ethic," said Djokovic. "Every time we got to play in the last three or four matches, it was some marathon, thrilling encounters.

"It's semi-finals so I'm expecting a tough battle. He's in very good form. He loves to play on this surface. He played finals last year, beat Roger (Federer) and myself.

"He's a grand slam champion, obviously that's a huge boost for him. If I manage to play as well as I did today and show up with a high quality of tennis, I think I have a good chance to win. I'm just hoping I can start off the match as well as I did today."