NEW YORK (AP) -- Ana Ivanovic kept her hot streak rolling with a straight-set victory to start the U.S. Open.

The eighth-seeded Serb beat American Alison Riske 6-3, 6-0 in the first round Tuesday. Ivanovic has won 48 matches this year, more than anyone else on tour.

The 2008 French Open champion has struggled to get back to that level but finally seems to be inching closer. She returned to the top 10 this month for the first time in more than five years.

Ivanovic was broken in the first game Tuesday but quickly took control.

The 24-year-old Riske made a breakthrough at last year's U.S. Open, reaching the fourth round after an upset of Petra Kvitova. She reached a career-high ranking of No. 40 this summer.

-- Rachel Cohen, AP NEWS

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