Jakub Mensik pulled off the biggest win of his career so far at the ATP 500 event in Doha, Qatar, on Thursday, stunning world number two Jannik Sinner in the quarter-finals 7-6, 2-6, 6-3.

The 20-year-old Czech will face Arthur Fils, who earlier defeated fellow Czech Jiri Lehecka, for a place in the final.

Mensik began the match aggressively, confidently holding his opening service game. After falling behind 0-40 in the next game, he responded with two strong serves and a composed volley to level the score. Sinner had a chance to break again, but Mensik held firm at the net and secured a 2-1 lead.

For much of the first set, both players held serve comfortably, trading powerful shots. Mensik earned the first break point of the match in the eighth game but narrowly missed, allowing Sinner to level at 4-4. The set eventually went to a tie-break, where Mensik’s big first serve proved decisive. An early mini-break and an unforced error from Sinner put him ahead 6-3, and he closed the set with a brilliant down-the-line backhand on his first set point.

In the second set, Mensik started well with a break-point opportunity in the opening game, but Sinner saved it with a strong serve. The Czech struggled with his first serve as Sinner gained momentum, breaking Mensik after two consecutive double faults and taking the set 6-2.

The decisive third set saw Mensik reignite his intensity. He immediately broke Sinner’s serve and consolidated the lead despite a few errors, extending to 2-0. He maintained the break advantage throughout the set, eventually sealing the victory on Sinner’s serve to record the biggest triumph of his career.

Despite some inconsistency in recent matches, Mensik has proven he can rise to the occasion against the sport’s elite. The win improves his record against top-five opponents to 4-2 and top-10 players to 9-8, while keeping him unbeaten in ATP events this season.

Doha marks Mensik’s second tournament of 2026, following a title-winning run at the Auckland ATP event in January. He now boasts 10 consecutive wins, including a run to the Australian Open round of 16, which he had to skip previously due to an abdominal injury.

The Czech first made his breakthrough in Doha two years ago, reaching the final against Karen Khachanov and breaking into the Top 100. Now, in his second appearance in the Qatari capital, Mensik has a chance to reach another final.

While an all-Czech semi-final was possible, Lehecka fell to Fils, meaning Mensik will meet the Frenchman in the semis. The other semi-final features world number one Carlos Alcaraz against defending champion Andrey Rublev.