NEW YORK -- Ana Ivanovic kept her hot streak rolling with a straight-set victory to start the US 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.
"The confidence is on a high level," she said. "I had a great season behind me."
The 24-year-old Riske made a breakthrough at last year's US Open, reaching the fourth round after an upset of Petra Kvitova. She reached a career-high ranking of No. 40 this summer.
Ivanovic upset Williams to reach the Australian Open quarterfinals. She was playing well heading to Roland Garros but lost in the third round to Lucie Safarova.
In her last tuneup before coming to New York, Ivanovic beat Sharapova in the semifinals in Cincinnati before losing to Williams in the title match.
Seventh-seeded Eugenie Bouchard routed Olga Govortsova 6-2, 6-1 on Tuesday in first-round play. At her previous major tournament, Bouchard made history at Wimbledon as the first Canadian to reach a Grand Slam final.
But she was swept away by Kvitova 6-3, 6-0, and things didn't go much better in her hard-court tuneups for the US Open, going 1-3 in her past three tournaments.
But against the 117th-ranked Govortsova, she had little trouble. Govortsova, who has been ranked as high as 35th, had won just two main draw WTA matches this year.
Svetlana Kuznetsova lost her first-round match at the US Open for the first time since 2005, the year she was the tournament's defending champion.
Kuznetsova, seeded 20th this time, was beaten 3-6, 6-2, 7-6 (3) on Tuesday by 82nd-ranked Marina Erakovic of New Zealand.
Kuznetsova called her quick exit "disappointing" and "shocking."
The 29-year-old Russian is a two-time major champion: She won titles at Flushing Meadows in 2004 and at the French Open in 2009.Information from The Associated Press was used in this report.