Top-seeded Roger Federer cruised in the tiebreakers to beat German qualifier Florian Mayer 7-6(2) 7-6(1) for a place in the Mercedes Cup semi-finals in Stuttgart on Friday - while also earning a new slice of ATP Tour history.
Federer struggled in some parts of the match but was at his best when most needed. He saved a set point to force the second tiebreaker, and fired a powerful forehand to clinch the match. "I am very happy to have made it two sets," Federer said.
His next opponent will be rising star and third-seeded Dominic Thiem, who beat him in the third round of the Italian Open before Federer went on a month-long break that included the French Open because of a back injury.
Thiem, from Austria, came from behind to beat Mikhail Youzhny of Russia 3-6 6-4 7-5.
Federer fired 15 aces to gain his 1072nd win on the tour, surpassing Ivan Lendl for second place in the Open era behind Jimmy Connors with 1256.
"It's crucial to serve well in a tiebreaker," Federer said. Two months shy of his 35th birthday, Federer is looking for his first title of the year following knee surgery and the back problem. "It's good to be back and to win two matches," he said.
Thiem, a semi-finalist at the French Open, said he was surprised to find himself at the same stage on grass.
"I really didn't expect it. But against Roger on grass, I'm not expecting anything," Thiem said.
Seventh-seeded Philipp Kohlschreiber beat qualifier Radek Stepanek 6-4 7-5 and will face Juan Martin del Potro in the other semi-final.
Del Potro, who is coming back gradually from wrist surgery, overcame fourth-seeded Gilles Simon 6-7(3) 6-3 6-0.