Williams defeated Mandy Minella 6-1, 6-3 in 57 minutes. The French Open champion started the match by holding serve at love and, after Minella won a game, reeled off five straight games to take the first set in 20 minutes.
Minella posted a break for a 2-0 lead in the second but Williams retook the advantage in winning four consecutive games -- including a run of 14 straight points won -- and closed the match with her fifth break of the day.
Williams extended her personal winning streak to 32 matches by winning 81 percent of the points on serve, despite the service break. She didn't drop a point on serve in the first set and had seven games serving that she won at love.
She moves into the next round against Caroline Garcia, who defeated Zheng Jie 6-3, 6-4 Tuesday and who has never made it past the second round of a major tournament.
World No. 4 Agnieszka Radwanska needed just 55 minutes to dispatch Yvonne Meusburger. Radwanska ended up with six breaks in seven receiving games and was charged with just eight unforced errors.
No. 10-seeded Maria Kirilenko became the second women's Top 10 player to exit Wimbledon. She was beaten by Great Britain's Laura Robson 6-3, 6-4. Fifth-seeded Sara Errani was eliminated in Monday's play.
Karolina Pliskova also won in an upset, beating 13th-seeded Nadia Petrova 6-3, 6-2. Tsvetana Pironkova dropped one game in forcing No. 21 Anastasia Pavlyuchenkova out of the tournament. Also, Alison Riske advanced when 31st-seeded Romina Oprandi retired in the third set.
Unseeded winners included Madison Keys, Olga Puchkova Jana Cepelova, Maria Teresa Torro-Flor, Alexandra Cadantu, Urszula Radwanska, Mathilde Johansson, Annika Beck, Petra Martic, Barbora Zahlavova Strycova, Peng Shuai, Simona Halep, Kaia Kanepi, Marina Erakovic, Elena Vesnina and Kimiko Date-Krumm, who, at age 42, became the second oldest woman to win a match at Wimbledon.