Williams was on the court 56 minutes is dispatching Carla Suarez Navarro 6-2, 6-0. Williams won four of the first five games and held serve in a 10-point game that began the eight-game winning streak.
She lost nine points in seven games serving in setting a personal match winning streak record of 22 straight. Her previous best of 21 in a row was reached for the third time Thursday.
Third-seeded Victoria Azarenka got past No. 9-seeded Samantha Stosur 6-4, 1-6, 6-3 in a match that saw 12 breaks. Azarenka won four of five games to get to 2-5 in the third and then fought off three break points to hold for the match.
Simona Halep, a tournament qualifier, gained a semifinal spot by ousting Jelena Jankovic 4-6, 6-0, 7-5. The match turned in the second set when Halep allowed Jankovic just 10 points. There were nine breaks in the 12 games of the third set.
Williams draws Halep in the first of Saturday's semifinals. Williams won a three-set challenge from Halep in 2011 in their only previous meeting. Azarenka is 5-1 all-time versus Errani.