Seventeen-year-old Justin Engel reached the Stuttgart Open quarter-finals on Thursday to become the youngest player since Boris Becker, 40 years ago, to reach the last eight of an ATP Tour grass-court tournament.
The German wildcard beat American seventh seed Alex Michelsen 6-4 6-4 to continue a stunning week for the teenager.
Engel had earlier became the second youngest player since 1990 to win an ATP Tour match on all three surfaces – grass, clay and hard court – after Rafael Nadal.
He now follows in the footsteps of compatriot Becker, who reached the quarter-finals at Wimbledon as a 17-year-old in 1985.
Engel will next play Felix Auger-Aliassime for a place in the semi-finals.
Meanwhile, German top seed Alexander Zverev beat Frenchman Corentin Moutet 6-2 7-6 (9-7) to also reach the last eight.
“I prefer to win 6-2 6-2, but you can never choose these kind of things. In the end I won and that’s the most important thing,” said Zverev.
“I think the first match on grass was never easy. I honestly think it was a very average match. I made it complicated, but a win is a win and I’m happy to play tomorrow again.”
