Jim Courier has two big doubts about Jannik Sinner.

Jim Courier, winner of two Australian Opens just like Jannik Sinner, spoke about the South Tyrolean, extolling him but also cautioning him: “He has everything he needs at the level of his game and above all he knows he can win on all surfaces, and that is the most important thing. Many past champions had that tapeworm, Sampras or McEnroe with Roland Garros, or Lendl at Wimbledon. He knows he can win anywhere and that gives him confidence. Having said that, it’s going to be tough: you have to stay healthy and you have to get through Carlos Alcaraz, his biggest challenge. But there is no doubt that he is more than capable, as is Alcaraz.”

“He has already made a huge change in his prime percentage towards the end of last season, after the US Open – added the’former tennis player, now commentator, on the online version of Gazzetta dello Sport -: there was margin there and he seems to have already filled it. So I would say the net game: maybe that is the area where there is still room for growth. I’m not sure how much stronger he can get, because serve and response last year were already number one on the tour, and from the back he is very solid and dangerous. He also added more bunts, and that was a nice change. The net game can still grow: we saw that with Djokovic as well, who improved a lot in that fundamental when he was around 30. In any case, Jannik is really close to perfection.”

Also holding court is the duel for world No. 1: “The computer is emotionless. These discussions about who is really number one leave time for them. It’s simple: how did you play in the most important moments? Did you win more Slams than others? The fact that Jannik was still in the running for number one despite missing three months by suspension last year was shocking, as strong as he was. My feeling is that Sinner had an incredible 2025, but the computer doesn’t lie: whoever ends the year number one is because he deserves it.”

He closed on the relationship between the top two players in the world: “Friendships are either real or they are not: I think they are friends and rivals at the same time, and they are on good terms with many others in the locker room as well. Tennis is a traveling circus: you travel together all the time, on a private plane or on a commercial flight”.

“I understand that sometimes people want some bitterness between rivals, but Evert-Navratilova are the perfect example of huge rivalry without animosity, as is Federer-Nadal. You can have respect and even friendship, and at the same time get on the court and try to smash their heads in when you play against them”.