The 17-year-old Alexander Zverev reached the semi-finals of his hometown ATP tournament by defeating Tobias Kamke 0-6 7-5 6-3 in the Hamburg Open on Friday.
Zverev earned just six points in the opening set, but he saved seven of 11 break points and converted four chances to beat his fellow Hamburg resident in two hours.
The 285th-ranked Zverev is the first 17-year-old to reach an ATP semi-final since 2006, when Marin Cilic lost to Feliciano Lopez at Gstaad.
Zverev, who has beaten Robin Haase, No.5 seed Mikhail Youzhny and No.11 Santiago Giraldo, must now overcome top seed David Ferrer, who beat fellow Spaniard Pablo Andujar 6-0 6-2.
Argentina's Leonardo Mayer defeated Serbia's Dusan Lajovic 6-1 7-5 for a semi-final with seventh-seeded German Philipp Kohlschreiber who beat Czech Lukas Rosol 6-4 6-4.
