Roger Federer eased into the semi-finals of his home-town Swiss Indoors in Basle with a comfortable 6-3 6-2 win over Andy Roddick.
The defending champion will face his compatriot Stanislas Wawrinka in the last four.
World number one Novak Djokovic was given a scare by Marcos Baghdatis before booking his semi-final place.
Djokovic eventually came through 2-6 6-2 6-3 and will meet Japan's world number 32 Kei Nishikori.
The defeat for an out-of-form Roddick was his 21st in 23 meetings against Federer and ends his hopes of reaching the World Tour finals in London later this month.
"It was a tough day for Andy, he wasn't at his best," said Federer, who is bidding to win a second title this season after winning in Doha at the start of the year. "This is the only match where he didn't serve well against me."
Federer finished off Roddick's challenge with back-to-back aces, his third and fourth, in his first tournament since mid-September.
"It didn't seem like he was so much into his game. My game got better as I went along, especially on serve. I'm pleased to be into another semi-final and facing Stan is always tough."
Federer has lost only once against Wawrinka, his gold medal-winning Beijing Olympic doubles partner.
Earlier in the day, Djokovic had his service broken twice early on before recovering to seal a victory that took his record against Baghdatis to 6-0, and put his 2011 record at 67-3.
"I started slowly, no life on the court, and he took his chances," said the Serb, who is playing his first tournament after a six-week break to heal a back injury. "My body is still getting used to this competition mode. I have to stay patient.
"It's nothing I didn't expect, but I'm winning matches and that is what matters most."
Baghdatis, who is now 59th in the world, hit six aces in dominating the first set but Djokovic broke for a 4-2 lead in the second after the Cypriot double-faulted and went on to control the rest of the match.