Peng claimed a 6-2, 6-7 (4-7), 7-6 (7-4) decision in a marathon 2 hours, 32 minutes. Both players had a pair of third-set breaks before Peng edged ahead in the tiebreaker.
Kirsten Flipkens took another long three-set upset win, eliminating sixth-seeded Francesca Schiavone 2-6, 6-3, 7-6 (7-3). Schiavone didn't face a break point in the first set but was broken twice in the second set as Flipkens evened the match. Again, both players had two breaks in the final set.
Fourth-seeded Yaroslava Shvedova got past Lourdes Dominguez Lino 6-4, 6-1 and Chanelle Scheepers had six breaks in a 6-1, 6-2 win over Alize Cornet.
Mona Barthel rallied for a 2-6, 6-0, 6-1 win over Ashleigh Barty, winning 11 consecutive games over the second and third sets. Even though the match went three sets, it took just 70 minutes.
Chipotle plans first price increase in 3 years
Justin Bieber crashes Drake Bell's album release party