Jakub Mensik turned 21 on the first day of the 2026 US Open fortnight, which is roughly the pace at which everything in his career has arrived. He had a Masters 1000 title before he had a driving licence in most of Europe, a Grand Slam semifinal before he had a top-10 ranking, and a major trophy in an event he had never played before in his life. The Czech is seeded 17th in New York and has never been past the third round here.
Prostejov and a Coach Who Stayed
Mensik was born on 1 September 2005 in Prostejov, the Moravian town that has produced a disproportionate share of Czech tennis players, and he still lists it as home. He met Tomas Josefus there at the age of eight, when Josefus was one of three coaches working with him at the town’s junior training centre. Josefus became his head coach when Mensik was 14 and has stayed in the chair through the whole climb.
That continuity matters more than it sounds, because the player Josefus first coached bears little resemblance to the one on court now. Josefus has said that in the under-14s Mensik stayed back on the baseline, pushed the ball, and waited for opponents to miss. The aggression was built, not inherited.
The Game
At 6ft 5in, Mensik serves the way tall players are supposed to and often do not: with a loose, unhurried motion that produces pace without visible effort, and with enough placement to keep returners guessing rather than simply blocking. He is right-handed with a two-handed backhand, and the backhand down the line is his most reliable rally-ending shot from the ground.
Josefus describes him as “an aggressive baseliner for sure”, a game built on a big serve and a big return and on taking time away from the opponent. The logic is arithmetic: on hard courts a large majority of points end within four shots, so a player who wins the first two exchanges wins most of the match. Mensik is built for exactly that, which is why his results skew toward hard courts and why he is a more dangerous opponent in the opening games of a set than in the twentieth.
The forehand is the wing that has lagged, and Josefus has said publicly that they know it and are working on it. In long rallies against elite movers, it is the shot that breaks down first.
Miami, 2025
Mensik made his Grand Slam debut at the 2023 US Open, reached the third round and lost to Taylor Fritz. He reached his first tour final in Doha in 2024, where Karen Khachanov beat him 7-6(12), 6-4 — the first-set tiebreak alone ran to 26 points. The breakthrough came in March 2025 at the Miami Open, where at 19 he beat Novak Djokovic 7-6(4), 7-6(4) in the final for his first ATP title.
Two tiebreaks, no breaks of serve, against the most accomplished returner in the sport’s history. It was the clearest possible statement of what his game is: hold, hold, hold, and win the two points that matter at the end of each set. He added a second title at the 2026 ASB Classic in Auckland, beating Sebastian Baez 6-3, 7-6(7).
2026 — Paris, and a Trophy Nobody Expected
Mensik reached the fourth round at the Australian Open and then produced the best result of his career at Roland Garros, reaching the semifinals on a surface that theoretically blunts everything he does well. He beat Joao Fonseca 6-4, 6-3, 7-6 in the quarterfinals before losing to Alexander Zverev in four sets. He reached a career-high world No. 12 on 2 March 2026.
Then came the strangest line on his record. Paired with Karolina Muchova in the revamped US Open mixed doubles event, Mensik won a major title in a discipline he had never competed in. The Czech pair saved two match points against Andrey Rublev and Mirra Andreeva in the semifinals, then beat Belinda Bencic and Flavio Cobolli 6-3, 1-6, 10-6 on Arthur Ashe Stadium. Mensik said afterwards he had a 100 percent win rate in mixed doubles and might retire on it.
Season Snapshot — 5 September 2026
The figures below move week to week and are current as of the date in this heading.
- ATP ranking: No. 18 (31 August 2026); career high No. 12
- ATP Tour titles: 2 — Miami 2025, Auckland 2026
- Best major result: semifinal, Roland Garros 2026
- Major titles: US Open mixed doubles 2026, with Karolina Muchova
- US Open 2026 seeding: 17
The US Open Problem
For all of it, Flushing Meadows has stayed shut. Mensik reached the third round in 2023 and 2024 and has never gone further, which is an oddity for a player whose game is built for American hard courts. He came through the first two rounds in 2026 without much trouble, beating Shintaro Mochizuki 6-1, 6-4, 7-5 and Jurij Rodionov 6-3, 3-6, 6-2, 6-3.
The third round on Saturday 5 September paired him with Learner Tien, the No. 14 seed, in a contrast of methods: Mensik trying to end points inside four shots, Tien trying to extend them until the Czech forehand has to hold up. The section they are playing in has already lost its highest seed: Felix Auger-Aliassime, seeded third, went out in the second round to Karen Khachanov, who won 6-7, 6-3, 6-2, 6-2.
More profiles are collected in the GTN player profile index, and the tournament itself is covered in the US Open guide. For how the No. 17 seeding was arrived at, see how tennis seeding works.
