Top-seeded Carlos Alcaraz of Spain lost for just the second time this year on Thursday, when 25th-ranked Jiri Lehecka of the Czech Republic beat him 6-3, 3-6, 6-4 in the quarterfinals of the Qatar Open.

Alcaraz's only other defeat in 2025 came at the hands of Novak Djokovic in the Australian Open quarterfinals. The 21-year-old Spaniard, currently ranked third in the world, won the Rotterdam Open earlier this month.

"I've talked with my team, with my coach, and honestly I don't know what I could have done better," Alcaraz said at the post-match press conference. "Honestly, I don't know. It was kind of a difficult feelings, I guess. I have to give credit to him as well, because when he was down, especially in the third set, he didn't give up."

Alcaraz led 4-2 in the third set and had a break point opportunity against Lehecka's serve, but couldn't finish off the Czech, who claimed the next three games to clinch his advancement to the semifinals.

The 23-year-old Lehecka will next face eighth-seeded Jack Draper of Great Britain, who knocked out Matteo Berrettini of Italy 4-6, 6-4, 6-3.

"The match was up and down since the beginning," Lehecka said after beating Alcaraz. "So for me to win a match like that against a player like this is a super big achievement. I believed in myself. I knew that I had the level to produce that kind of tennis. I didn't back down. I wanted to push him to his limits. The way I trusted my game was the key today."

Earlier, fifth-seeded Andrey Rublev of Russia saved one match point and needed eight of his own to subdue second-seeded Alex de Minaur of Australia 6-1, 3-6, 7-6(8). Rublev earned a fourth semifinal appearance in Doha, where he won the title in 2020.

He will next face Canada's Felix Auger-Aliassime, who beat Daniil Medvedev when the Russian retired due to illness after dropping the first set 6-3.