Roger Federer beat Florian Mayer 7-6 (7/2), 7-6 (7/1) on Friday to reach the Stuttgart grass semi-finals with another tennis record.
The world number three moved ahead of Ivan Lendl to stand sole second in career match wins as he earned his 1,072 victories to place behind Jimmy Connors (1,256) in the table.
Federer dispatched Germany's Mayer for the seventh time without a loss as he advanced into a final four showdown with Austrian Dominic Thiem, who recovered to defeat Russian Mikhail Youzhny 3-6, 6-4, 7-5.
Federer is playing for the first time in a month after dealing with the back pain which forced him to skip the French Open.
His last Stuttgart appearance was a decade and a half ago when the event was an indoor Masters.
Federer advanced with 15 aces in 80 minutes to stand 13-4 on the season. Thiem's success is only his 10th career ATP-level grass match.
But the ATP number seven said he has achieved more this week than he had imagined.
"It's not nice to play Roger on any surface. he is the best on grass. Against him, I have no expectations."
The 22-year-old said that beating an injured Federer a month ago on clay in Rome meant nothing.
"I can win on clay, that is my surface and I feel very confident against almost all players," he said.
"But grass is different for me. I'm unbelievably happy with this semi-final, anything that comes now is a big bonus."
Thiem now stands 4-6 on grass as he scored his first back-to-back wins on the lawns with 11 aces.
"This was the biggest win of my career on grass," Thiem said after advancing in just under two hours over the 2002 winner (on clay) at the Weissenhof Club.
"I won a tight match against a very good and very experienced grass player.
"There were a lot of ups and downs, I was close to losing in the second set with break points and at 5-5 in the third.
"I'm happy with my fighting spirit and happy with this whole win."
Thiem dropped the opening set as he lost the eighth game. But the youngster regained his poise quickly to win the second with a break of Youzhny in the final game.
He took victory with a concluding break of the Russian in the final game of the match with a forehand winner on second match point.
In other quarter-finals, French fourth seed Gilles Simon was taking on Juan Martin Del Potro and German seventh seed Philipp Kohlschreiber was to play veteran qualifier Radek Stepanek.