Sinner stunned in Doha — how Jakub Mensik's upset reshapes the Qatar Open field

The shock win by Jakub Mensik in Doha changes who has real momentum in this week’s event and who must recalibrate. Mensik’s victory removes the tournament favorite and hands a major opportunity to rivals waiting in the bottom half — and sinner is the name everyone will be measuring coming out of the quarter-finals. The immediate implication: the path to the title is suddenly less predictable and more open.

Immediate impact: momentum shifts, seed expectations and the altered semi-final picture

Mensik’s quarter-final victory forces several immediate adjustments. A player who had just ended a long unbeaten stretch is out, which reshuffles projected matchups and the psychological landscape for the remaining contenders. Arthur Fils — the unseeded Frenchman who beat Jiri Lehecka 6-3 6-3 — now faces Mensik for a spot in an ATP final; the winner will reach another late-stage match with fresh momentum. Elsewhere in the draw, top players who advanced will now approach the weekend knowing the tournament favorite is gone.

Here's the part that matters: tournament math and player confidence are both altered. A lower-ranked player has taken a major scalp, creating a rare opening that other seeds and unseeded challengers can exploit.

What's easy to miss is Mensik’s profile coming into this week — young, seeded but not among the very top names — which makes this result a sharper signal about depth of competition than a routine upset.

Match details — Jakub Mensik ends Sinner run in three sets

Jakub Mensik, the sixth seed and a 20-year-old from the Czech Republic, beat world number two Jannik Sinner in the quarter-finals, winning 7-6 (7-3) 2-6 6-3. That result ended a run of 22 wins from 23 matches for sinner; the only loss in that spell had come last month against Novak Djokovic in the Australian Open semi-finals. Mensik is listed at world number 16 and will now meet Arthur Fils for a place in the final.

Other quarter-final outcomes left world number one Carlos Alcaraz and fifth seed Andrey Rublev on course to meet in the opposite semi-final after both won their last-eight ties, and a separate doubles draw keeps a pair of British teams in contention. The doubles semi-finals also advanced top seeds who have history at this venue, adding another layer of interest to the weekend schedule.

• Mensik beat Sinner 7-6 (7-3) 2-6 6-3 — Sinner’s 22-from-23 streak ended.
• Mensik is the sixth seed and is around world number 16 in the rankings.
• Arthur Fils, unseeded, beat Jiri Lehecka 6-3 6-3 and now faces Mensik in the semi-final.
• Carlos Alcaraz and Andrey Rublev won their quarter-final matches and are set to meet in the other semi-final.

The real question now is how the remaining favorites respond: do they see the draw as an opportunity, or will the shock widen into more unpredictable results? Momentum in a tournament like this can be contagious; a single upset often gives other lower-seeded players belief.

• Key takeaways: Mensik’s win makes the bottom half of the draw more open.
• The dismissal of the pre-tournament favorite shifts short-term betting of form and confidence among contenders.
• Fils versus Mensik is now a pivotal semi-final; the winner reaches an ATP final this season.
• Top seeds in the opposite half still present a strong challenge, keeping the event competitive across both sides of the draw.

Micro timeline (relevant points from recent coverage):

• 2025: The player at the center of this upset reached 10 finals during that season and captured major titles.
• Last month: that player’s only recent defeat in a long winning run came at a Grand Slam semi-final loss to Novak Djokovic.
• Doha quarter-final: Mensik beat Sinner 7-6 (7-3) 2-6 6-3 to advance to the semi-finals.

Expectations and confidence now become the primary currencies over the next two days. If Mensik keeps elevating his level the rest of the field will have to react quickly; if he stumbles, the narrative swings back to established top seeds. The real test will be how quickly the remaining players translate this upset into changed tactics and renewed focus.