Azarenka, the reigning Australian Open champion, needed only 68 minutes to win her quarterfinal, breaking Pervak's serve seven times.
Pervak opened the tournament with an upset win over former No. 1 Caroline Wozniacki, but didn't have anything left to trouble Azarenka after coming off consecutive third-set tiebreakers.
The third-ranked Williams faced fellow American Sloane Stephens in a night quarterfinal. Williams has won 33 of her last 34 matches, including titles at Wimbledon, the Olympics and U.S. Open. She has an 11-1 record against Azarenka, including a 5-0 mark in 2012.