"I wouldn't say it's a relief, because a relief is something else, but I'm pleased to be in the semis," Federer said. "I knew it was going to be difficult because in the beginning I only had one hour of practice here. But now I feel good and I'm not too tired."
Federer, who fired 18 aces and had 33 winners overall, will next play last year's runner-up and local favorite Gael Monfils, who beat third-seeded Andy Murray 6-2, 2-6, 6-3.
Murray ran out of gas and struggled on his first serve in the decider, allowing Monfils to make the decisive break in the fifth game after the 23-year-old Scot made two consecutive unforced errors.
Andy Roddick lost the serving contest against Robin Soderling, who had 18 aces in the 7-5, 6-4 win.
