Third seed Alexander Zverev suffered a surprise defeat against Frenchman Ugo Humbert at the Halle grasscourt tournament on Thursday, the third seed going down 7-6(4) 3-6 6-3.
A first set dominated by serve inevitably went to a tiebreak in which Humbert pulled clear to move ahead.
Germany's Zverev grabbed an early break in the second set which proved sufficient to level the match.
But he could not sustain the momentum as Humbert took charge of the deciding set with some aggressive hitting.
He will next face Sebastian Korda in the quarter-finals after the American knocked out Kei Nishikori.
Published 17 June 2021, 17:26 IST