World number one Jannik Sinner had to go the full distance before outlasting Jan-Lennard Struff 6-2, 6-7 (1-7), 7-6 (7-3) on Friday for a place in the semi-finals of the Halle grass court tournament.
Sinner failed to convert all of his 11 break points in the second and third set against Struff, who fired 18 aces, before eventually prevailing in the final tie-break after 2 hours 30 minutes.
"It was a very tough match. I had chances in the second, had chances in the third, but couldn't use them. It was 0/40 [in the first game of the third set]. I just try to accept these kind of challenges," Sinner said.
In the semis, the Italian faces either American Christopher Eubanks or Zhang Zhizhen of China.
There was more joy for the hosting Germans when French Open runner-up and twice Halle runner-up Alexander Zverev needed the same amount of time as Sinner when he rallied to beat 37th-ranked Frenchman Arthur Fils 6-7 (5-7), 6-3, 6-4.
"I love playing here. Tennis has given me so much. When I get to play in a full stadium in Germany, I'm the happiest person in the world," Zverev said.
He next faces Poland's Hubert Hurkacz, who ousted American Marcos Giron 7-6 (7-5), 6-4, and is yet to drop a set in Halle.
Halle is among the big tune-up tournaments for Wimbledon which starts on July 1.