San Francisco Frontiers - Tsitsipas battles past valiant Griekspoor in Rotterdam

The world number 12 eventually overcame spirited resistance from the Dutchman with a 6-7 (7-5), 7-6 (8-6), 7-5 victory in a match lasting around three hours.

"I feel like I was here for 10 hours today. I felt like me and Tallon played for ages and I feel like it was a marathon. We started yesterday and finished today," he joked.

"I always felt that he brought the best out of me. We were both fighting pretty well out on the court. These are matches that are going to be remembered."

Tsitsipas now faces a quarter-final clash with Italian qualifier Mattia Bellucci, who shocked second seed Daniil Medvedev in a marathon three-setter on Wednesday.

To the delight of the home crowd, it was the Dutchman who took the initiative in the first set, breaking the Tsitsipas serve in the fifth game with an extraordinary crosscourt forehand pass.

Griekspoor consolidated his advantage with a comfortable hold and served for the set at 5-3 but a costly backhand error and a Tsitsipas winner got the Greek back on serve.

The Dutchman raced into a 5-1 lead in the tie-break and while Tsitsipas battled back to within one point, Griekspoor held his nerve to take the first set with a powerful serve.

Griekspoor's first-set heroics seemed to have taken a lot out of him and he appeared fatigued at the start of the second set, which went with serve until the tie-break.

The second tie-break was nip and tuck, Griekspoor cleverly mixing up serve and volley tactics with solid baseline groundstrokes.

He had a point to clinch the match but Tsitsipas snuffed out his hopes with an unreturnable serve and a wild backhand from Griekspoor gifted the Greek the set.

With a renewed spring in his step, Tsitsipas broke the Dutchman's serve immediately in the third set. A tiring Griekspoor fought valiantly, roared on by the crowd, and broke back in the eighth game.

At 4-4, Griekspoor saved more break points and somehow held serve, taking the game after the rally of the match, whipping a top-spin forehand past his higher-ranked opponent.

But Tsitsipas held firm, sealing the match with a crosscourt forehand winner.

Also through to the quarter-finals in the bottom half of the draw was last year's runner-up Alex de Minaur, who defeated Czech teenager Jakub Mensik 6-4, 6-4.

Top seed Carlos Alcaraz will be hoping to avoid Medvedev's fate when he takes on another Italian qualifier, Andrea Vavassori in Thursday's late-night match.

H.King--SFF