DUBAI, United Arab Emirates — Tallon Griekspoor saved four match points before beating top-seeded Daniil Medvedev 2-6, 7-6 (7), 7-5 to reach the semifinals at the Dubai Championships on Thursday.

“When I won the second set, I was actually thinking ‘how am I even still in this tournament?’ I probably should have been on the plane to Indian Wells already,” said the Dutchman, ranked No. 47. “Sometimes you’ve got to be a little bit lucky.”

Griekspoor had survived a first-round encounter with Roman Safiullin by saving three match points. He then eliminated defending champion Ugo Humbert on Wednesday.

“It’s my best win by ranking,” Griekspoor said after his quarterfinal victory over No. 6 Medvedev. “Just very pleased with this win. It means a lot.”

Griekspoor will meet fourth-seeded Stefanos Tsitsipas for a shot at the title. Tsitsipas beat Matteo Berrettini 7-6 (5), 1-6, 6-4.

Felix Auger-Aliassime defeated 2014 US Open champion Marin Cilic 6-4, 3-6, 6-2 to set up a semifinal against qualifier Quentin Halys, who eliminated Luca Nardi 2-6, 6-3, 7-6 (5).