The top-seeded Wozniacki needed 66 minutes to defeat 27th-seeded Jarmila Gajdosova of Australia 6-3, 6-2 and move on to her next match against Dominika Cibulkova of Slovakia.
The seventh-seeded Williams cruised past Russia's Maria Kirilenko 6-3, 6-2 and advanced to a clash with 2007 runner-up Marion Bartoli of France. The ninth-seeded Bartoli got past Italy's Flavia Pennetta.
Williams, who has been battling health issues, has a 17-match winning streak at Wimbledon.
Sharapova, the No. 5 seed, upended Klara Zakopalova of the Czech Republic earlier in the day. Sharapova broke her opponent's serve five times and scored 20 winners.
Sharapova will next face Peng Shuai of China, who advanced with a win over Melinda Czink of Hungary.