Serena Williams encountered late resistance from a teen champion on Wednesday before the Wimbledon winner polished off Nicole Gibbs 6-2, 6-1 in her first match at the WTA Stanford Classic.
World number four Williams was fighting off jet lag as well as reigning US college champion Gibbs, an American ranked 403rd in the world and a junior at Stanford University, host of the $740,000 hard court event.
It took defending champion Williams, who enjoyed a first-round bye, only 62 minutes to advance.
"I couldn't quite believe I was playing today, but I'm healthy, I have a heartbeat, so there was no reason not to," Williams said.
"I'm sure I'll feel better after a day off. I've been waking up at 2:00am. I was sluggish today, but it was fine to get that win over with.
The winner of 14 career grand slam singles titles, Williams will next play a quarter-final against South African sixth seed Chanelle Scheepers, who beat Portugal's Michelle Larcher de Brito 6-3, 6-4.
Williams returned to California on Monday, arriving 48 hours after winning her fifth Wimbledon title.
She will return to Europe late next week to train in Paris before traveling to the London Olympics, which begin on July 27.
Belgian fifth seed Yanina Wickmayer ended the British challenge for the week with her defeat of Heather Watson 5-7, 6-1, 6-4.
American Coco Vandeweghe, ranked 120th in the world, produced the first big upset of the week with a 6-4, 6-2 victory over former world number one Jelena Jankovic - who double-faulted to set up a match point.
The defeat was the third straight in an opening round for the Serb, who just began working with her third coach this season in an effort to rescue a ranking which has fallen to 20th since she topped the WTA list in 2008.
AFPTags: tennis, sport, united-states First posted July 12, 2012 15:37:36