The 17-year-old Alexander Zverev reached the semifinals of his hometown 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 semifinals since 2006, when Marin Cilic lost to Feliciano Lopez at Gstaad.
Zverev has also beaten Robin Haase, fifth-seeded Mikhail Youzhny and 11th-seeded Santiago Giraldo. He next faces top-seeded David Ferrer, who eased past Spanish compatriot Pablo Andujar 6-0, 6-2.
Argentina's Leonardo Mayer defeated Serbia's Dusan Lajovic 6-1, 7-5 and the seventh-seeded Philipp Kohlschreiber of Germany later beat Czech player Lukas Rosol 6-4, 6-4 to complete the other semifinal.
