"Felix Auger-Aliassime didn't believe in himself"-Serena Williams' ex-coach Rennae Stubbs says Canadian's inner doubts fueled US Open defeat to Jannik Sinner

Felix Auger-Aliassime's defeat to Jannik Sinner at the 2025 US Open semifinals was analysed by Serena Williams' ex-coach Rennae Stubbs. In a recent episode of her podcast 'Edge of Our Seats', Stubbs opined that the Canadian was possibly plagued by inner doubts that led to his semifinal loss at the hardcourt Major.

Auger-Aliassime had previously reached a Grand Slam semifinal four years ago, at the 2021 US Open. He came into his own at this year's edition of the Grand Slam event with consecutive wins over Alexander Zverev, Andrey Rublev and Alex De Minaur before falling to Jannik Sinner. Impressed by his form, Stubbs believed the only thing that held Auger-Aliassime was the lack of a winning mindset.

"The way that Felix served, the way that he showed up on the forehand side, on everything, he would just relax. I think the thing that stopped him beating Jannik was the fact that he didn't truly believe in himself," she said.

She added that while it might not have been apparent on the outside, Auger-Aliassime was probably not as confident going into the match.

"People say, 'What do you mean?' but it's true. I've talked about this on the podcast, the subconscious, conscious mind. The conscious mind is like, 'yeah I can win this match,' and the subconscious mind is like, 'can you Felix? can you really? You're not really as good as this guy.'

To Felix Auger-Aliassime's credit, he did manage to take a set off the World No. 2 who eventually won the match 6-1, 3-6, 6-3, 6-4. After his semifinal run, the 25-year-old has jumped up 14 spots to become the current World No. 13.

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Serena Williams ex-coach highlights Felix Auger-Aliassime "honestly" dismissing his years earlier winning record over "AI generated" Jannik Sinner

Felix Auger-Aliassime at the 2025 French Open. Image: Getty

Serena Williams' ex-coach Rennae Stubbs attempted to gauge Felix Auger-Aliassime's mentality ahead of his 2025 US Open semifinal clash against Jannik Sinner. She cited the example of his pre-match interview dismissal of having a winning record over Sinner on her podcast to show that the Canadian should have shown more confidence.

The head-to-head between the two players stood at 2-1 in Felix Auger-Aliassime's favor at the time, now levelled at 2-2 after Jannik Sinner's US Open semifinal win.

"Even in the prematch interview he said, you know when someone brought up the fact that he had a winning record over Jannik, he was like, well, you know, that was a lot of years ago. And it's like no dude, you should be like yeah I'm going to kick his a**," she said.

However, Stubbs was appreciative of Auger-Aliassime's honest reflection their first 2 encounters, that the latter won, came in 2022 before the 4-time Grand Slam champion had lifted a trophy at a Major.

"And he's so nice that he's actually honest about, 'but that was a couple of years ago' before Jannik turned into this AI project of a human being on the tennis court and never loses," she added.

Jannik Sinner has been called an AI generated player before in jest by Alexander Bublik after the Italian defeated him in the fourth round of the US Open in an hour and 21 minutes. However, despite his near-perfect form Sinner fell to this year's US Open champion Carlos Alcaraz in the final.