Wozniacki crushes Stephens
Caroline Wozniacki produced a performance of real authority to beat hotly-tipped American Sloane Stephens 6-1 6-0 in under an hour in Miami.
The one game Stephens won was a service break, but 11th seed Wozniacki had her way with the 21-year-old's serve throughout.
With fiance Rory McIlroy watching from the stands, Wozniacki seemed keen to return to his company and allowed Stephens to win only five points in a hopelessly one-sided second set.
Venus Williams, by contrast, was kept on court for two hours and 18 minutes by Australian wild card Casey Dellacqua before finally prevailing 6-4 5-7 6-4.
Dellacqua had won 23 of her previous 27 matches and battled back from a set behind and from 4-2 down in the third, but Williams finally got over the line.
She will face 10th seed Dominika Cibulkova, who similarly needed almost two and a quarter hours to battle past France's Alize Cornet as she eventually won 7-6 (8/6) 6-4.
Other seeded players had a somewhat easier time, second seed Li Na beating American Madison Keys 7-6 (7/3) 6-3 and third seed Agnieszka Radwanska defeating Elena Vesnina 7-5 6-3. It was Li's first match in the tournament, following a first-round bye and a walkover against Alisa Kleybanova.
Varvara Lepchenko battled past Ajla Tomljanovic 6-4 6-7 (4/7) 7-6 (7/2) to set up a clash with Wozniacki, Spain's Carla Suarez Navarro won 6-2 6-1 against Estonia's Kaia Kanepi and Ukrainian Elina Svitolina beat Barbora Zahlavova Strycova 4-6 6-4 6-1.