Martin Klizan of Slovakia saved five match points against sixth-seeded Roberto Bautista Agut to set up a semi-final with French qualifier Nicolas Mahut at the World Tennis Tournament on Friday.
Klizan was on the brink of defeat but converted a break point with a superb forehand return down the line to level at 5-5 in the second set and prevailed 6-7 (7-5) 7-6 (8-6) 6-0 in a match that lasted nearly three hours.
Another stunning forehand winner sealed the second set tiebreak and Bautista Agut ran out of gas in the decider, winning just 16 points before bowing out.
"It was a real battle out there", said world No.43 Klizan after ending a four-match losing streak against the Spaniard.
"Despite Roberto's match points, I kept fighting, because it isn't over until it's over. Of course you could see that Roberto played a lot of matches before."
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Bautista Agut has already won two titles this season, in Auckland in January and Sofia last week.
Mahut dispatched eighth-seeded Viktor Troicki 6-2 6-1 to reach the semi-finals while Philipp Kohlschreiber upset second-seed and one-time US Open champion Marin Cilic 3-6 6-3 6-4 to advance.
Mahut, the oldest player in the draw at 34, lost just three points on his first serve, saved the three break points he faced, and broke world No.22 Troicki four times.
Mahut, who is seeking a fourth career title, has now won five matches in a row in Rotterdam.
"Maybe I should file a request for more tournaments in Holland," he said.
"It seemed as if Viktor was a bit tired after playing the final in Sofia last week. But things are going well for me here in Rotterdam, as I'm in the doubles semi-finals as well."
Kohlschreiber will face the only seeded player left in the draw in the semi-finals.
Flamboyant Frenchman Gael Monfils the last man through to the semis with a 7-6 (7-4) 6-3 win over young German Alexander Zverev.
Monfils is coming off a final loss to fellow Frenchman Gilles Simon in Montpellier last week.
