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In a high-quality encounter, the Czech blew away Alcaraz at times with his destructive baseline hitting. The 23 year-old backed up 135mph first serves with pinpoint groundstrokes to gain the upper hand in baseline exchanges, and he showed mental toughness, rallying from 2-4 down in the third set to advance to the last four in Doha for the second time.

"I feel great," Lehecka said. "The match was up and down since the beginning. So for me to win a match like that against a player like this is a super big achievement. I believed in myself and knew I had the level to produce this kind of tennis. I knew if I could be a bit more consistent in matches, I can bring these results more and more.

"I think the most important part was I believed in my game and did not back down. Even when I was missing shots in the third set, I wanted to play my game style, be an aggressive player and push him to his limits. I was just waiting for the right moment to put all these things together and it happened when I broke him back in the third set."

Lehecka captured his second tour-level title in Brisbane in January and built on that strong early-season form by advancing to the fourth round at the Australian Open. The 23 year-old is up to No. 22 in the ATP Live Rankings after his latest run in Doha and is set to rise to a career-high on Tuesday.

Alcaraz entered the clash on a seven-match winning streak, having clinched the crown at the ATP 500 in Rotterdam. The 21 year-old was making his debut in Doha and dispatched Marin Cilic in the first round before he battled past Luca Nardi.

The top seed hit a number of stunning passes and defended well out of the corners during the two-hour, nine-minute clash against Lehecka. Yet, his timing was off at times and Lehecka was aggressive in the key times to triumph.

Into his ninth tour-level semi-final, Lehecka clenched his fists and let out a roar following match point. He then embraced the roars from the crowd and applauded Alcaraz off court.

Lehecka will next face British lefty Jack Draper on Saturday.

"I will try to recover well and get back on the right track in the morning to build the right things again," Lehecka said. "I am confident I can bring even more tomorrow and I will try my best."

Draper will rise to a career-high on Tuedday after he reached his ninth tour-level semi-final. The 23 year-old moved past Matteo Berrettini 4-6, 6-4, 6-3 in two hours and 22 minutes and is just two wins away from his third ATP Tour title.

Draper, who is up to No. 14 in the ATP Live Rankings, is making his debut in Doha and is now 16-2 against players outside the Top 20 since the 2024 US Open.