© Ina FASSBENDERGermany's Alexander Zverev is into the second week of the ATP tournament in Cologne
Fresh from winning the ATP tournament in Cologne last weekend, Germany's Alexander Zverev reached the quarter-finals of the second week on the Rhine with a tough, three-set triumph over John Millman of Australia on Wednesday.
Zverev, 23, ranked seventh in the world, needed nearly two hours to post a 6-0, 3-6, 6-3 victory over the 31-year-old Millman.
The German top seed will meet France's Adrian Mannarino in Friday's quarter-finals.
On Thursday, Japan's Yoshihito Nishioka, who saw off Britain's Kyle Edmund on Tuesday, will play Germany's Jan-Lennard Struff for a last-eight place.
Seventh-seed Struff beat Italy's Marco Cecchinato 6-3, 6-1 in the first round.
Cologne's Lanxess Arena is hosting back-to-back ATP events.
Zverev defeated Canada's Felix Auger-Aliassime last weekend in the final of the first event.
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