The defending champion won her opening match Tuesday, relying on an overpowering serve to beat 17-year-old Michelle Larcher de Brito of Portugal 6-0, 6-4.
Williams won all 27 points on her first serve and hit 15 aces, the last on her final shot. As the crowd applauded her victory, Williams curtsied, mindful Queen Elizabeth II is expected to visit Wimbledon for the first time since 1977 on Thursday.
Williams plays her second-round match that day and has been practicing her curtsy.
"I want it to be more natural," she said. "Right now it feels really forced. Seems like I've never done a curtsy before, which may be true. But I'm looking forward to nailing it."
The queen won't get to see French Open runner-up Samantha Stosur, who lost to qualifier Kaia Kanepi 6-4, 6-4. Stosur came into the tournament ranked a career-best sixth.
Roland Garros winner Francesca Schiavone lost Monday.
Two-time Grand Slam champion Svetlana Kuznetsova edged Akgul Amanmuradova 6-2, 6-7 (5), 6-4. No. 7-seeded Agnieszka Radwanska defeated Melinda Czink 6-3, 6-3, and No. 10 Flavia Pennetta swept Anabel Medina Garrigues 6-4, 6-0.
In men's play, No. 10 Jo-Wilfried Tsonga beat Robert Kendrick of the United States, 7-6 (2), 7-6 (8), 3-6, 6-4. American James Blake, returning from a three-month layoff because of a knee injury, lost to Robin Haase 6-2, 6-4, 6-4.
American Sam Querrey, who won his first career grass-court title at Queen's this month, advanced when Sergiy Stakhovsky retired because of illness trailing 7-6 (4), 6-3, 2-1. Stakhovsky won the grass title this month at Den Bosch, Netherlands.
No. 13 Mikhail Youzhny defeated Dudi Sela 6-3, 6-4, 4-6, 7-6 (2). No. 19 Nicolas Almagro lost to Andreas Seppi 7-6 (4), 7-6 (7), 6-2.
Williams played first on Centre Court and remained unbeaten in opening Grand Slam matches. She's 43-0 in the first round at major events.
For her return to Wimbledon on a warm, sunny afternoon, the three-time champion wore a cream dress with red trim.
"Strawberries and cream," she said.
Larcher de Brito, ranked 148th, has three wins over top-20 players but was overwhelmed at the start, needing 33 minutes to win a game.
The teenager then began to play better, and grunts that accompanied her shots grew louder. Last year, French Open opponent Aravane Rezai complained that Larcher de Brito's shrieks were too loud, and the noise drew considerable attention from the British media at Wimbledon.
Williams grunted, too. There were some vigorous rallies down the stretch, with Larcher de Brito holding her own as both players scrambled along the baseline.
"She definitely packs a punch," Williams said. "It was good for me because most people that do play nowadays hit really hard. It was good to get someone that hit really hard early on."
Williams packed the bigger punch — she finished with 47 winners to six for Larcher de Brito, many on serves. In the final game, Williams hit a service winner and three aces to close out the victory.
Williams said poor serving cost her when she was upset by Stosur in the quarterfinals at the French Open.
"I served so terrible my last match at the French," Williams said. "I went home and worked really hard on my serve. I was incredibly disappointed with it. Had a talk with my serve. I said, 'You know, we got to do a little bit better.'"
Williams reached double figures in aces for the eighth time this year, most on the women's tour. She has won 58 of her past 59 matches against players ranked outside the top 100.