Shanghai, Oct 2 : World No. 2 Jannik Sinner admitted he is expecting "a difficult and tough challenge" in his Shanghai Masters title defense which begins against Germany's 49th-ranked Daniel Altmaier, who triumphed in five sets in their latest meeting at Roland Garros in 2023.

The 24-year-old Italian defeated teenager Learner Tien to clinch his 21st ATP title in Beijing. Within hours of his triumph, he travelled south to Shanghai.

'I have only one practice session to get ready, but let's see,' Sinner was quoted by ATP as saying. 'It's going to be a very, very difficult and tough challenge, especially the first (match)... You never know what's going to happen.'

The Shanghai Masters will be missing World No. 1 Carlos Alcaraz, who pulled out citing "physical issues". That leaves four-time Shanghai champion Novak Djokovic as the biggest obstacle to Sinner's repeat bid.

Last year, Sinner memorably beat Djokovic in the final to lift the Shanghai trophy, marking one of the biggest victories of his career. Yet the Italian, who has confirmed he will only have one practice session before his opening match, is focused from the outset.

After his US Open final defeat to Carlos Alcaraz, which also cost him his World No. 1 spot. , Sinner hinted at subtle changes in his game. Those tweaks, he says, are beginning to pay off, but he remains hungry for more.

'I'm not the only one who is changing,' Sinner said in his pre-tournament press conference in Shanghai. 'If you ask every player, every player is changing stuff and trying to get better. Whatever we try to do, it's not crazy steps, just trying to adjust a couple of things, trying to get better as a player, like everyone else does. Certain shots that worked slightly better than the months before, certain shots we can still improve.

'But it's also normal, and I'm just looking forward to having as many matches as possible in every tournament. This gives me the chance to try as many things as possible. So, let's see, but we are quite happy with the work we are doing.'

/IANS