Jannik Sinner’s biggest weakness has become apparent despite quarterfinal win

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Jannik Sinner has qualified for another Grand Slam semifinal.

The Italian didn’t drop a set in the quarterfinals, as Sinner defeated Ben Shelton, 6-3, 6-4, 6-4.

However, as dominant as the scoreline looks, it doesn’t tell the whole story.

During the latter stages of the second set, Sinner seemed out of sorts.

He almost looked dazed on Rod Laver Arena, perhaps struggling with the conditions just as he did earlier in the tournament.

Commentating for BBC Radio 5 Live, British tennis legend Annabel Croft shared her thoughts.

“Even with that last point, Sinner was not hitting with the same authority, not the same depth or sound out of the racquet, and he’s taking a lot of time in between [points],” she said.

“He’s slowed up and looks a bit hot, like he’s not feeling so well.”

For all his success in Melbourne, the heat continues to trouble the two-time champion.

It’s up to his opponents to start taking advantage of what is fast becoming a glaring weakness in his game.

Jannik Sinner struggles in the heat – How can his rivals make the most of it?

Sinner is a four-time Grand Slam champion and has previously held the world number one ranking for 66 weeks.

He’s been near-perfect since 2024, but near-perfect and perfect are two very different things.

His issues with the Melbourne heat are evidence of that, as Sinner has now suffered twice this tournament.

During his third-round match against Eliot Spizzirri, Sinner cramped up badly and was saved by the enforced heat break, which allowed him to head inside.

He then fought back to win in four sets, but against a different opponent, Sinner could have been in real trouble.

And that wasn’t the first time he’d encountered problems either, as the 24-year-old struggled against Holger Rune in the fourth round of the Australian Open last year.

Many believed an upset was on the cards when the Dane took the second set, as Sinner began shaking on court.

However, just as he did against Spizzirri and Shelton, Sinner recovered to secure the win.

He has yet to lose because of the heat, but surely there’s only a matter of time before someone exposes his weakness.

Perhaps his semifinal opponent, Novak Djokovic, will do just that.

But how can the Serb take advantage?

Well, he won’t really need to change much, as Djokovic’s game is well known for tiring out his opponents.

Pushing them side to side with long lung-busting rallies, the 38-year-old has exhausted many a rival during his career.

A prime Djokovic would cause real problems for a heat-affected Sinner, but luckily for the Italian, he won’t be playing prime Djokovic in the semifinals.

The Serb, while still one of the best players in men’s tennis, isn’t quite the dominant force he once was.

And, Djokovic has a major blister on his foot, which could impede his movement against Sinner.

However, while Djokovic may not be able to capitalise on Sinner’s weakness, others now know the game plan.

If you’re playing Sinner in Melbourne, no matter how hard things get, keep pushing, because there are some real question marks over his ability to withstand the heat.

How many matches has Jannik Sinner won in a row at the Australian Open?

On the other hand, when fully fit and healthy, Sinner is almost unbeatable down under.

He has won his last 22 matches at the event, winning titles in 2024 and 2025.

• 1. 2024 Australian Open 1R [WIN] vs Botic van de Zandschulp, 6-4, 7-5, 6-3
• 2. 2024 Australian Open 2R [WIN] vs Jesper De Jong, 6-2, 6-2, 6-2
• 3. 2024 Australian Open 3R [WIN] vs Sebastian Baez, 6-0, 6-1, 6-3
• 4. 2024 Australian Open 4R [WIN] vs Karen Khachanov, 6-4, 7-5, 6-3
• 5. 2024 Australian Open QF [WIN] vs Andrey Rublev, 6-4, 7-6, 6-3
• 6. 2024 Australian Open SF [WIN] vs Novak Djokovic, 6-1, 6-2, 6-7, 6-3
• 7. 2024 Australian Open F [WIN] vs Daniil Medvedev, 3-6, 3-6, 6-4, 6-4, 6-3
• 8. 2025 Australian Open 1R [WIN] vs Nicolas Jarry, 7-6, 7-6, 6-1
• 9. 2025 Australian Open 2R [WIN] vs Tristan Schoolkate, 4-6, 6-4, 6-1, 6-3
• 10. 2025 Australian Open 3R [WIN] vs Marcos Giron, 6-3, 6-4, 6-2
• 11. 2025 Australian Open 4R [WIN] vs Holger Rune, 6-3, 3-6, 6-3, 6-2
• 12. 2025 Australian Open QF [WIN] vs Alex de Minaur, 6-3, 6-2, 6-1
• 13. 2025 Australian Open SF [WIN] vs Ben Shelton, 7-6, 6-2, 6-2
• 14. 2025 Australian Open F [WIN] vs Alexander Zverev, 6-3, 7-6, 6-3
• 15. 2026 Australian Open 1R [WIN] vs Hugo Gaston, 6-2, 6-1 (RET)
• 16. 2026 Australian Open 2R [WIN] vs James Duckworth, 6-1, 6-4, 6-2
• 17. 2026 Australian Open 3R [WIN] vs Eliot Spizzirri, 4-6, 6-3, 6-4, 6-4
• 18. 2026 Australian Open 4R [WIN] vs Luciano Darderi, 6-1, 6-3, 7-6
• 19. 2026 Australian Open QF [WIN] vs Ben Shelton, 6-3, 6-4, 6-4

Only time will tell if he can pick up his 20th consecutive win in the semifinals.

Sinner will play Djokovic in the Australian Open semifinals on Friday, January 30.