Serena Williams beat Australia's Anastasia Rodionova 6-0, 6-0 on Tuesday in the first round of the Bank of the West Classic.
Williams, troubled by a right foot injury the past year, played on American soil for the first time since reaching the semifinal of the 2009 U.S. Open. It's her third event since winning at Wimbledon last year.
Williams, ranked 169th, moved smoothly on the court against the overmatched, 105th-ranked Rodionova, who has lost five straight.
In other first-round matches, Russian Maria Kirilenko beat sixth-seeded Julia Goerges of Germany 6-2, 6-3; seventh-seeded Ana Ivanovic of Serbia, playing her first match with a new coach and fitness trainer, was knocked off by Japan's Ayumi Morita, 6-3, 7-5; Slovakia's Daniela Hantuchova beat newcomer Rina Fujiwara of Japan, 6-0, 6-2; Germany's Sabine Lisicki defeated Romania's Simona Halep, 6-1, 6-2; qualifier Marina Erakovic of New Zealand beat Sweden's Sofia Arvidsson, 6-2, 6-1; and Poland's Urszula Radwanska topped Ukraine's Olga Savchuk 6-2, 6-4 in a matchup of qualifiers.
The 25th-ranked Kirilenko, who reached the quarterfinal of this event last year, snapped a 13-match losing streak against the top 20 with her victory. She'll play Williams next.
"She's coming back and she's winning again," Kirilenko said of Williams. "I need to be focused every minute."
Kirilenko is a five-time WTA Tour singles champion and is looking for her first title since 2008.
Goerges, ranked 20th, won her first Premier WTA singles title at Stuttgart earlier this year.