Tallon Griekspoor staged a grand recovery, saving four match-points, before stunning top seed Daniil Medvedev 2-6, 7-6(7), 7-5 to reach the semi-finals of the Dubai Championships on Thursday.
Griekspoor saved three match-points against qualifier Roman Safiullin in the first round before eliminating defending champion Ugo Humbert in the second on Wednesday.
“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.”
“It's my best win by ranking,” said Griekspoor after his quarter-final win over world No. 6 Medvedev.
“Just very pleased with this win. It means a lot.”
He will meet fourth seed Stefanos Tsitsipas, who beat Matteo Berrettini 7-6(5), 1-6, 6-4.
In the other quarter-finals, Canada's Felix Auger-Aliassime defeated 2014 US Open champion Marin Cilic of Croatia 6-4, 3-6, 6-2 to set up a semi-final with French qualifier Quentin Halys, who eliminated Italy's Luca Nardi 2-6, 6-3, 7-6(5).