Jannik Sinner found it "mentally tough" to come from behind and defeat Roman Safiullin at the China Open.

Sinner forged a second straight comeback to prevail 3-6 6-2 6-3 on Saturday.

The world number one, who equalled Alexander Zverev by picking up his 57th win of 2024, ensured he kept up his run of reaching at least the quarter-finals in every ATP Tour-level tournament he has reached this season.

But he certainly did not find it easy against the world number 69.

"A tough match. He’s an incredible player and we always have tough battles," said Sinner. 

"This was our third encounter, so we know each other a bit. He returns very well, and he was serving well at important moments. So I tried to keep up mentally, which today was very tough.

"Especially on these kinds of days, when maybe you don’t feel at your 100%, to find a way through means so much to me.

"He's an incredible player, so I knew I had to raise my level when it counted."

While Sinner was on court, the World Anti-Doping Agency (WADA) announced it would be appealing against the decision to clear the Italian of blame after he twice tested positive for a banned substance.

WADA claimed last month's ruling, which was made by an independent tribunal, which found Sinner had no case to answer was "not correct", and the organisation has now appealed to the Court of Arbitration for Sport (CAS), seeking a ban of between one and two years for the 23-year-old.

Sinner "Obviously I'm very disappointed and also surprised of this appeal because we had three hearings. All three hearings came out very positively for me.

"I knew it a couple of days ago, that they were going to appeal, that today it's going to go official."