Jakub Mensik is enjoying the week of his life at the Qatar ExxonMobil Open.

The #NextGenATP Czech earned his first Top 5 win on Thursday in Doha, where he stunned World No. 5 Andrey Rublev 6-4, 7-6(6) to reach his maiden tour-level semi-final.

Mensik was competing in his first tour-level quarter-final having beaten former World No. 1 Andy Murray in the second round in the longest match in tournament history (three hours and 23 minutes). The 18-year-old backed that up in style, playing aggressively in the crucial moments to stun the top seed Rublev, who went 0/6 on break points in the match.

"It's just been an incredible week from the beginning I played very well and I knew I could play with the big players. It's an amazing feeling to reach the semi-finals after beating those good players,” Mensik said.

"But the job is not done yet. Hopefully I can play like this again in the semis tomorrow and go on to make the final."

With his one-hour, 38-minute win, the 18-year-old jumped to No. 94 in the Pepperstone ATP Live Rankings and will make his Top 100 debut on Monday.

In a tense tie-break, Rublev netted a routine mid-court forehand after a powerful first serve to go down a mini break at 6/7. Mensik took full advantage, confidently closing out the match on the next point, before he dropped to his haunches in delight.

Mensik is the youngest player to defeat a Top-5 player since Carlos Alcaraz overcame Stefanos Tsitsipas at the US Open in 2021. Mensik will continue his title quest against Ugo Humbert or Gael Monfils in the semi-finals.

Mensik took advantage of a Next Gen Accelerator Programme wild card into the ATP 250 as part of new opportunities for players aged 20 and under.

Players inside the Top 350 receive up to eight ATP Challenger Tour 100 and 125 opportunities. But as a Top 250 player Mensik also receives one wild card into one ATP 250 main draw (and two ATP 250 qualifying events). He is making full use of his decision to use his main-draw wild card in Doha, which followed his semi-final run in the Bahrain Challenger last week.

"It's been a good choice to play the Arabian swing," Mensik said. "I'm so happy with the matches I got last week and this week. It's incredible for young players to have the opportunity to play these tournaments."

It has been a successful week on the ATP Tour for several #NextGenATP stars. In Los Cabos, 19-year-old American Alex Michelsen stunned Top 10 star Alex de Minaur to reach the quarter-finals, while in Rio de Janeiro, 17-year-old Brazilian Joao Fonseca became the first player born in 2006 to win a tour-level match when he downed Arthur Fils. Michelsen and Fonseca are both in action later on Thursday.

Rublev was aiming to win the title in Doha for the second time, having lifted the trophy in 2020. The 26-year-old is 11-3 on the season, highlighted by his title run in Hong Kong.