Matteo Berrettini claimed a comfortable win over Richard Gasquet on Thursday in Gstaad on his return to action after missing Wimbledon.
The Italian, who was runner-up at the All England Club in 2021, withdrew from the grass-court Grand Slam tournament last month after testing positive for Covid.
He had previously been in fine form, winning titles at Queen's and in Stuttgart.
Berrettini carried on where he had left off, easing past Gasquet 6-4, 6-4 to reach the quarter-finals of the clay-court event, where he won his maiden ATP title in 2018.
"I have great memories here," Berrettini said.
"My first ATP Tour title. I really like these conditions... Also I have a lot of people coming to support me.
"A lot of Italians, I heard, so I am really happy to be here and I am enjoying it."
The second seed will face Pedro Martinez for a semi-final spot.
French Open losing finalist Casper Ruud cruised past Czech Jiri Lehecka 6-3, 6-4 to set up a last-eight tie with Jaume Munar.
Injury-hit former US Open champion Dominic Thiem continued his comeback by reaching a second quarter-final in as many weeks.
The Austrian, now ranked 274th in the world, beat Federico Delbonis 7-6 (8/6), 6-3 and next plays Peruvian Juan Pablo Varillas.