Federer conqueror Tsitsipas returns with Sofia victory

Stefanos Tsitsipas recorded a straight-sets victory to progress to the last-eight.

Greek star Stefanos Tsitsipas at the Australian Open.

Stefanos Tsitsipas, who stunned Roger Federer on his way to a shock appearance in the Australian Open semifinals, made a winning return to action on Thursday, when he defeated Germany's Jan-Lennard Struff 7-6 (7/5), 6-4 to reach the Sofia Open quarterfinals.

Second seed Tsitsipas hit 10 aces on the way to victory in his first match since losing to Rafael Nadal in the semifinals in Melbourne last month.

The world number 12 will face seventh-seeded Frenchman Gael Monfils, who moved through by defeating Mikhail Kukushkin 7-5, 6-3, for a place in the last-four.

“I will have to be careful,” said Tsitsipas, who stunned 20-time major winner Federer in the last-16 at the Australian Open.

“My opponent does unpredictable things on the court. Sometimes you don't expect things and he'd play, I'd say, with your mind.

“He has seen my game, I have seen his... I just need to be careful and be aware of what he's doing,” the Greek star told www.atp.com .