Unseeded Jakub Mensik of the Czech Republic recorded a 6-4, 7-6 (6) upset over top-seeded Andrey Rublev on Thursday to advance to the semifinals of the Qatar ExxonMobil Open in Doha.

Mensik, 18, reached his maiden tour-level semifinal after firing 10 aces to dispatch the Russian in 98 minutes. The victory over the World No. 5 marked Mensik's first Top 5 win in his career. He is the youngest player to accomplish that feat since Carlos Alcarez of Spain toppled Stefanos Tsitsipas of Greece at the U.S. Open in 2021.

Mensik will continue his quest for glory against France's Gael Monfils, who posted a 6-2, 6-4 win over countryman and third-seeded Ugo Humbert. With Thursday's win, the 37-year-old Monfils became the oldest semifinalist in tournament history.

Also on Thursday, Australian Alexei Popyrin posted a 6-4, 6-4 win over fourth-seeded Alexander Bublik of Kazakhstan. Popyrin will face Russian Karen Khachanov, who led 3-0 over Emil Ruusuvuori before the Finland native retired from the match due to injury.

Rio Open

Second-seeded Cameron Norrie of Great Britain cruised into the quarterfinals in Rio de Janeiro with a 6-1, 6-1 victory over Tomas Barrios Vera of Chile.

Norrie converted six of 10 break-point opportunities, compared to 1 of 3 for his opponent. Norrie also dominated first serve points at 16 of 21 (76 percent) to 6 of 21 (29 percent) for Barrios Vera.

Fifth seed Sebastian Baez beat fellow Argentine Facundo Diaz Acosta 7-6 (1), 6-3, and sixth seed Dusan Lajovic upset fellow Serbian Laslo Djere, the sixth seed, 6-2, 7-5.

Other winners were Brazil's Joao Fonseca and Thiago Monteiro, both wild-card entrants, Brazil's Thiago Seyboth Wild and qualifier Mariano Navone of Argentina. Fonseca, 17, is through to his first career quarterfinal.

Mifel Tennis Open

Australia's Jordan Thompson avoided an upset, rallying from a first-set bagel to beat the United States' Alex Michelsen 0-6, 7-6 (1), 7-5 in the quarterfinals in Los Cabos, Mexico.

Thompson, the eighth seed, had more aces, 6-2, and winners, 20-8. He converted all three of his break-point opportunities, while Michelsen was 5 of 16.

No. 4 Casper Ruud of Norway handled Nuno Borges of Portugal, 6-3, 6-2 before the top two seeds both advanced in straight sets. No. 2 Stefanos Tsitsipas of Greece downed Aleksandar Kovacevic of the United States 7-6 (1), 6-3, and No. 1 Alexander Zverev of Germany ousted Australia's Thanasi Kokkinakis 6-3, 6-4.