Germany's Alexander Zverev reached the semi-finals on home turf in Halle with a 7-6 (12-10), 7-6 (7-2) win over Belgian qualifier Raphael Collignon on Friday.
The French Open champion converted his second match point after almost exactly 2 hours.
In front of a well-filled Centre Court, the top seed and the qualifier played out a hard-fought match. Both players impressed with strong serving, hitting 14 aces apiece.
"It was an incredible match, a high level from both players," Zverev said. "It could also have gone two sets the other way."
Zverev has made the semi-finals at the Wimbledon warm-up for the fourth consecutive time but has never won at the western German event.
His next opponent Taylor Fritz earlier got a revenge of sorts when he saved a match point to beat fellow US star Ben Shelton in a dramatic quarter-final.
Fritz won six days after losing the Stuttgart final against left-hander Shelton. He also lost the Dallas final in February against Shelton and trails their series 3-2.
This time he prevailed 6-7 (5-7), 7-6 (10-8), 7-6 (7-3) in 2 hours 49 minutes in sweltering conditions, saving the match point at 7-6 in the second set tie-break.
Fritz fired 24 aces and saved four break points while Shelton faced no break point and had 15 aces.
“I don’t know if I could have taken losing another one of those to Ben,” Fritz was quoted by the ATP as saying on-court.
“When I say that, I mean just doing everything but winning the match, because the funny thing about this one is he had the chances. In the other two he won, I probably had the better chances. I kind of just had it in my head capitalizing on the big chances and I am happy to get through that.”
Fourth seed Daniil Medvedev was beaten by German journeyman Daniel Altmaier in the third quarter-final, much to the joy of the Halle crowd.
Altmaier outlasted the Russian 6-4, 6-7 (6-8), 6-4 for a famous home victory.
He plays second seed Felix Auger-Alliasime or Frances Tiafoe in Saturday's last four as the prospect of an-all German final ramps up.
Wimbledon starts a week on Monday.
