Flipkens edged past Ajla Tomljanovic 4-6, 6-4, 7-5, not securing the match until the final game when she notched her fifth break of the day.
After Tomljanovic won the first set, Flipkens evened things with a late break in the second. Both players had breaks in the third set before Flipkens got the final break and moved to the quarterfinals.
Ekaterina Makarova took out second-seeded Marina Erakovic 7-6 (8-6), 3-6, 6-0. She lost her serve twice in the first set but only in tying the score in the second and didn't face a break point in finishing off the match with the third-set shutout.
No. 3-seeded Sorana Cirstea lost 16 points in 10 games serving while beating Tsvetana Pironkova 6-4, 6-4 and fifth-seeded Sabine Lisicki was on the court just 56 minutes in a 6-4, 6-2 romp over Kristyna Pliskova.
Daniela Hantuchova beat seventh-seeded Laura Robson 6-3, 6-4 while winning two-thirds of the points on serve. Also in the second round, Mirjana Lucic-Baroni routed ninth-seeded Yanina Wickmayer 6-4, 6-0 and qualifier Alla Kudryavtseva topped 14th-seeded Heather Watson 6-4, 6-3.
No. 12-seeded Kristina Mladenovic was a 6-4, 6-1 winner over Johanna Konta; No. 13 Bojana Jovanovski rallied for a 4-6, 6-1, 6-4 win over Andrea Hlavackova; No. 15 Francesca Schiavone beat Nadiya Kichenok 7-6 (7-4), 6-2 and 16th-seeded Magdalena Rybarikova just got by Mathilde Johansson 7-5, 6-7 (4-7), 6-4 in a match that took 2 hours, 47 minutes.
Maria Sanchez came out ahead 7-6 (7-3), 6-3 over Alison Van Uytvanck in a match sending two qualifiers against each other.