Jakub Mensik defeated Jannik Sinner 7-6, 2-6, 6-3, in the quarterfinals of the Qatar Open.
The win was the biggest of his career so far (by ranking) as he stunned the world number two.
Mensik is no stranger to causing upsets on the ATP Tour, having already picked up nine top-10 wins.
Is it time to start worrying about Jannik Sinner yet?
He has not looked himself in 2026…
He’s undoubtedly one of the brightest prospects in men’s tennis.
Can he challenge Sinner and Carlos Alcaraz on a regular basis and help form a new big three?
It’s tough to say…
But he has a better chance than Joao Fonseca!
Jakub Mensik has already proven he can beat Grand Slam winners
Novak Djokovic, Rafael Nadal, and Roger Federer were better known as the ‘big three’.
The legendary trio won the majority of the Grand Slams they played, dominating for a generation.
Since Nadal and Federer retired, fans have been desperately searching for their replacements.
Alcaraz and Sinner fit the bill, but the third player has been harder to find.
Who will join Carlos Alcaraz and Jannik Sinner in a new ‘big three’?
Many backed Brazilian youngster Fonseca to join them, having impressed at times last year.
The teenager won titles in Buenos Aires and Basel, producing some breathtaking tennis at times.
But while he’s lifted a few trophies, he’s yet to beat any top players.
Fonseca has only beaten one top-10 player, Andrey Rublev, at the Australian Open a year ago.
Mensik, on the other hand, has a winning 9-8 record against top-10 players and is only a year older than Fonseca.
Jakub Mensik’s top-10 wins
| Match | Opponent | Opponent’s rank | Score |
| 2024 Qatar Open – QF | Andrey Rublev | 5th | 6-4, 7-6 |
| 2024 Madrid Open – 2R | Grigor Dimitrov | 10th | 6-2, 6-7, 6-3 |
| 2024 Shanghai Masters – 2R | Andrey Rublev | 6th | 6-7, 6-4, 6-3 |
| 2024 Shanghai Masters – 4R | Grigor Dimitrov | 10th | 6-3, 3-6, 6-4 |
| 2025 Australian Open – 2R | Casper Ruud | 6th | 6-2, 3-6, 6-1, 6-4 |
| 2025 Miami Open – 2R | Jack Draper | 7th | 7-6, 7-6 |
| 2025 Miami Open – SF | Taylor Fritz | 4th | 7-6, 4-6, 7-6 |
| 2025 Miami Open – F | Novak Djokovic | 5th | 7-6, 7-6 |
| 2026 Qatar Open – QF | Jannik Sinner | 2nd | 7-6, 2-6, 6-3 |
The Czech might not be as flashy or as exciting as Fonseca, but his results speak for themselves.
In the last 12 months, he’s beaten Djokovic, a 24-time Grand Slam champion, and Sinner, a four-time major winner.
When Mensik plays well, he really can beat anyone.
His serve is one of the best on tour, and it can cause problems for even the best returners around, as evidenced by his wins over Djokovic and Sinner.
So what’s stopping Mensik from joining Alcaraz and Sinner in a new big three?
Jakub Mensik lacks consistency on the ATP Tour
When he’s at his best, Mensik is a top-five player.
The issue is that he’s not at his best very often.
After winning the Miami Open last May, he seemed destined for a true breakout year, but that never quite transpired.
Mensik’s form was inconsistent, to say the least.
There were a few good weeks scattered among an array of early exits, as Mensik finished the year ranked 19th, having once sat seventh in the ‘Race to Turin’.
If he wants to become a top-10 player and challenge for Grand Slam titles, that level of inconsistency just won’t cut it.
The Czech needs to improve his physical fitness, shot-making, and focus to reduce his reliance on the serve.
Because when the serve isn’t there to bail him out, Mensik suddenly looks very beatable.
But that was last year, and 2026 Mensik looks ready to challenge!
Jakub Mensik hasn’t lost a match since the United Cup
Since going 1-2 at the United Cup in January, Mensik hasn’t lost a single match.
He won the ASB Classic in Auckland before reaching the fourth round of the Australian Open, where he withdrew due to injury.
Jakub Mensik at the ASB Classic (Wins 1-4)
- 1. 2026 ASB Classic 2R [WIN] vs Hamad Medjedovic
- 2. 2026 ASB Classic QF [WIN] vs Giovanni Mpteshi Perricard
- 3. 2026 ASB Classic SF [WIN] vs Fabian Marozsan
- 4. 2026 ASB Classic F [WIN] vs Sebastian Baez
Jakub Mensik at the Australian Open (Wins 5-7)
- 5. 2026 Australian Open 1R [WIN] vs Pablo Carreno Busta
- 6. 2026 Australian Open 2R [WIN] vs Rafael Jodar
- 7. 2026 Australian Open 3R [WIN] vs Ethan Quinn
Now, in Qatar, he’s won another three matches, taking his winning streak to 10.
Jakub Mensik at the Qatar Open (Wins 8-10)
- 8. 2026 Qatar Open 1R [WIN] vs Jan Choinski
- 9. 2026 Qatar Open 2R [WIN] vs Zhizhen Zhang
- 10. 2026 Qatar Open QF [WIN] vs Jannik Sinner
There aren’t many players in better form than Mensik right now.
It remains to be seen what the future holds for the 20-year-old…
Could he be crowned the Qatar Open champion on Saturday? Only time will tell.
First, he’ll play Arthur Fils in the semifinals on Friday, February 20.
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