STANFORD, Calif. (AP) -- Serena Williams had to get her bearings after flying halfway around the world.
Once she got loose, she needed just over an hour to pick up another win.
Four days after capturing the singles' title at Wimbledon, the fourth-ranked and top-seeded Williams beat reigning NCAA champion Nicole Gibbs 6-2, 6-1 in the second round of the Bank of the West on Wednesday.
"I couldn't quite believe I was playing today,'' Williams said. "But I'm healthy and I have a heartbeat so I didn't have a reason not to. I could have felt better.''
Gibbs double-faulted on her first serve and then seemed to regain her composure and played a number of strong points the rest of the way.
"I kind of expected that,'' Gibbs said. "I could laugh at that one. She is such a hero to me and I had her so built up in my mind I thought she was going to do no wrong. I collected a lot of experience points out there if not physical points.''
Williams, who credited her win at Stanford last year as rejuvenating her career, said it took some time to adjust to the different conditions between Wimbledon grass and California hard court.
"I definitely felt sluggish and it was good to get the win over with,'' she said. "I'm still waking up at 2 a.m.''
When Williams discovered that Gibbs once served as her ball girl and looked up to her, she was flattered.
"To know someone still wants to be like me, that's kind of awesome,'' Williams said. "When I played Monica Seles for the first time it was kind of cool.''
Gibbs will get another chance at a WTA Tour event, as she learned Wednesday she received a wild card into the main draw at San Diego next week.
"She held her own today,'' Williams said. "She moved well and she didn't quit and to me that's the best quality you can have as an athlete. She's a fighter and has a pretty good first serve.''
Williams will meet sixth-seeded Chanelle Scheepers of South Africa in Friday's quarterfinal. Scheepers advanced with a 6-3, 6-4 victory over wild card Michelle Larcher De Brito of Portugal.
In another match, fifth-seeded Yanina Wickmayer of Belgian beat Heather Watson of Britain 5-7, 6-1, 6-4.