Stosur beat Jamie Hampton 6-2, 6-4 in 65 minutes. She dropped 14 points over nine service games and didn't have to deal with a break point from Hampton. Stosur finished off three of her own 10 break opportunities.
She is the only seeded player to advance to Saturday's semifinals after seventh-seeded Chanelle Scheepers and No. 8-seeded Laura Robson lost Friday.
Chang Kai-Chen earned a shot at Stosur in the semis with a 6-4, 3-6, 7-6 (7-4) decision over Robson. Each player won two-thirds of the points on serve but Chang was able to eke out the win in the tiebreaker after a solid third set by both players.
Japan's Misaki Doi took out Scheepers 2-6, 6-1, 6-3 with three breaks in each of the second and third sets.
Heather Watson also earned a spot in the semis, beating Pauline Parmentier 7-5, 6-3. Watson won 55 percent of the points off Parmentier's serve, winning 7-of-18 break-point chances.
Stosur has never before played Chang but Watson is 2-0 versus Doi, having taken a pair of straight-set decisions last year.