Stan Wawrinka won his first ATP tour match in nearly four months, starting his Geneva Open title defense Wednesday with a 6-3, 6-4 victory over American Jared Donaldson.

Now ranked No. 25 after surgery and persistent problems with his left knee, Wawrinka lost his opening match at three previous tournaments since February.

The 33-year-old Swiss delighted home fans with a routine win under lights at the rain-hit clay-court event.

Wawrinka finally got on court for a second-round match against the 57th-ranked Donaldson more than 24 hours after it was scheduled, and never allowed a break-point chance.

The two-time defending Geneva champion is back on court Thursday for a quarterfinal against unseeded Marton Fucsovics of Hungary.

The final is Saturday in the last warm-up tournament for the French Open, which starts Sunday.