Belinda Bencic made a winning return to action as the Olympic champion defeated Zarina Diyas to seal a quarter-final spot at the Luxembourg Open.

Bencic, the unlikely successor in Tokyo, triumphed in straight sets 6-1 6-3 on Thursday to tee up a last-eight encounter with Liudmila Samsonova, who the Swiss lost to in Berlin earlier this year.

It was a welcome return to form for world number 12 Bencic after her defeat to eventual champion Emma Raducanu in the US Open quarter-finals last week.

Joining the top seed in the quarters is defending Luxembourg Open champion Jelena Ostapenko, who needed three sets to overcome Arianne Hartono.

Second seed Elise Mertens also progressed, though she had to come from behind to beat Aliaksandra Sasnovich 3-6 6-2 7-5.

In Thursday's other last-16 tie, Marie Bouzkova beat Greet Minnen to round off the quarter-finals line up.

Meanwhile, Sorana Cirstea and Jasmine Paolini will meet in the Zavarovalnica Sava Portoroz quarter-finals after respective victories over Tereza Martincova and Anna Kalinskaya.