SHANGHAI — Jo-Wilfried Tsonga won for the first time since retiring from his quarterfinal match at the U.S. Open, beating Florian Mayer 6-3, 6-2 Monday in the opening round of the Shanghai Masters.

Tsonga, who lost to Novak Djokovic in the Shanghai final last year, had 12 aces against Mayer and saved all five break points he faced.

The ninth-seeded Frenchman hasn't played since retiring with a knee injury against Djokovic at the U.S. Open last month after dropping the first two sets.

In other matches, rising German star Alexander Zverev and his older brother Mischa both moved into the second round with straight-set victories. Alexander, ranked No. 21, defeated John Isner 6-4, 6-2, while Mischa, who is coming off a quarterfinal appearance at last month's Shenzhen Open, beat Zhang Ze 6-1, 6-2.

Canadian qualifier Vasek Pospisil earned just his ninth victory of the season, edging Ivo Karlovic 7-6 (5), 6-4. He will attempt to win back-to-back matches for the first time this year against either Grigor Dimitrov or Richard Gasquet, who play their opening match on Tuesday.

Other winners included American qualifier Taylor Fritz, who beat Stephane Robert of France 7-6 (2), 2-6, 6-3, and Kyle Edmund of Britain, who earned a measure of revenge after his country's loss to Argentina in the Davis Cup semifinals by defeating Federico Delbonis 6-3, 5-7, 6-4.

Djokovic, the top-seeded player and three-time champion, plays his first match since his runner-up finish at the U.S. Open on Tuesday against Fabio Fognini of Italy. The Serb withdrew from last week's China Open, where he is a six-time champion, with an elbow injury.