Novak Djokovic saved five match points to beat Frenchman Florent Serra 5-7, 7-5, 6-1 and reach the last eight in the Halle tournament on Thursday.
The second seed's remarkable comeback means he joins five Germans in the quarter-finals, a feat they have not achieved since the 1973 Berlin tournament, tour organisers ATP said.
Serbia's world number four Djokovic, the highest-ranked player after the withdrawal of top seed Roger Federer, saved three match points at 5-2 and 0-40 in the second set.
He saved another match point a game later and one more at 5-4 before going through to face Austrian Juergen Melzer.
"It's a big lesson I learned today, to fight until the last point," a relieved Djokovic told reporters, adding he saved six match points at Wimbledon in 2005 to break into the top 100.
"This victory meant a lot to me back then," he said. "Hopefully, this win can do something as well. I am not playing even close to my best on this surface."
Struggling for much of the first two sets to find his rhythm on the grass court, the 22-year-old fired ground strokes long as Serra looked hungrier at the net and led by a set and 5-2.
But Djokovic won 11 of the next 12 games and after breaking to go 6-5 ahead he crossed himself, glanced up to the heavens and never looked back.
An early break and an audacious drop shot gave him a 3-1 lead in the third before he broke twice more to win in just over two hours as world number 56 Serra saw his game collapse.
"I was making too many big steps on this surface and was too unbalanced and too defensive," Djokovic said.
Andreas Beck became the fifth German to book a quarter-final spot after beating Slovak lucky loser Lukas Lacko 7-5, 7-6 to set up a clash against Philipp Kohlschreiber.
Fellow German Nicolas Kiefer could have boosted their numbers but retired with a muscle injury after losing the first set 6-1 to Melzer.
World number 59 Philipp Petzschner also failed to reach the last eight after losing 5-7, 7-5, 6-2 to Belgium's Olivier Rochus who meets German Benjamin Becker.
The hosts are already assured of one place in Sunday's final with four German quarter-finalists in the top half of the draw.