Andrey Rublev was stunned by Luca Van Assche in the quarter-finals of the Estoril Open on Friday, as the world number 78 teed up an all-French clash with Hugo Gaston.

Rublev had cruised to his most dominant win of the year in the round of 16 one day earlier, swatting lucky loser Timofey Skatov aside by a 6-1 6-1 scoreline in just 59 minutes. 

The top seed looked bound for the last four when he took the opening set of Friday's match, only for Van Assche to fight back for an eye-catching 3-6 6-3 6-4 success.

A hard-fought break in game four of the second set, in which Van Assche failed to convert three break points before making his fourth count, proved the turning point.

That was part of an 11-game run in which eight went the way of the 22-year-old, who is now into his first ever ATP-level semi-final.

He said afterwards: "I'm very, very happy about the win today. It's the best win of my career so far.

"It means a lot to me. I love Portugal. I've played well here, so far in my career. It's a place that I love and to be in the semi-finals... it's a great step."

Second seed Luciano Darderi and fourth seed Alexander Blockx are still lurking on the other side of the draw and could represent possible final opponents for Van Assche or Gaston.

Heading towards the title... why not? @EstorilOpen | #EstorilOpen | @lucavanassche pic.twitter.com/sZpW0gUXLS

— ATP Tour (@atptour) July 24, 2026

Elsewhere, 2025 Austrian Open champion Alexander Bublik sealed a return to the title match in Kitzbuhel by beating Tomas Martin Etcheverry 6-3 6-4.

Bublik could still repeat last year's feat of winning the title without dropping a set, having overpowered fourth seed Etcheverry in one hour and 25 minutes.

Quentin Halys will be Bublik's opponent in the showpiece match, having beaten Yannick Hanfmann 6-4 7-6 (7-2) in Friday's other semi-final.

Fourth time's a charm for Van Assche

Van Assche was playing in his fourth ATP Tour quarter-final, having lost each of his previous three. 

But it was a case of fourth time lucky for the Frenchman as his powerful forehand simply proved too hot to handle for Rublev in sets two and three.

Both players carved out 11 break points apiece throughout the contest, with Van Assche taking two of his opportunities and Rublev only able to make one count.