Defending champion Alexander Zverev moved into the quarter-finals of the BMW Open in Munich having come from behind to beat fellow German Yannick Hanfmann.
The top seed and World No 3 bounced back after wildcard Hanfmann - ranked 118th in the world - took the first set via a lengthy tiebreaker.
Zverev eventually posted a 6-7 (12) 6-4 6-2 victory and will face another compatriot in the next round in Jan-Lennard Struff, who beat another German, Yannick Maden, 6-3 3-6 6-3.
Alexander Zverev roars as he secures his place in the quarter-finals of the BMW OpeniPhone transfer software
South Korea's fourth seed Hyeon Chung progressed as he also overcame a German wildcard, easing past Matthias Bachinger 6-1 6-1.
He now takes on Slovakian qualifier Martin Klizan, who won 4-6 6-3 7-5 against Bosnia's Mirza Basic.
At the Millennium Estoril Open in Portugal, fourth