Injury ends Vesnina's bid
Elena Vesnina's Hobart International title defence came to a disappointing end after she was forced to retire with a hip injury.
Vesnina, the No 3 seed, was trailing 4-6 6-2 4-1 against Estrella Cabeza Candela when she decided she was unable to continue.
Vesnina, who was forced to miss the ASB Classic in Auckland with an ankle injury, wrote on Twitter: "Tried my best, but injury got worst during the match. Thank you @HobartTennis for warm welcome. And hope to see u next year. Off to Melbourne."
Fellow seeds Samantha Stosur and Kirsten Flipkens both survived scares to reach the next round.
Top-ranked Stosur overcame a second-set wobble to beat Kristina Mladenovic 6-4 2-6 7-6 (9-7), while second seed Flipkens held her nerve to outlast Storm Sanders 4-6 7-6 (7-3) 7-6 (7-5).
Stosur will now take on eighth-seed Bojana Jovanovski in the last eight, while Flipkens will take on either Garbine Muguruza or Yanina Wickmayer.
No 7 seed Klara Zakopalova was a convincing winner as she blew away Zhang Shuai 6-1 6-2 to set-up a quarter-final clash with Alison Riske.