Wozniacki suffered three breaks in the first set before coming back for a 4-6, 6-0, 6-3 win over Ekaterina Makarova. Wozniacki won about two-thirds of the points on serve after the first set, and finished off seven of her 12 break chances.
Elena Vesnina stopped Li 7-6 (7-4), 6-3. Vesnina had a pair of second-set breaks that were the difference in the match.
Hampton and Wozniacki are scheduled for the first semifinal Friday while Vesnina and Wickmayer are paired in the second.