The top-ranked Sabine Lisicki struggled through a three-setter to remain alive in the Auckland Classic as other seeds crashed around her in a rain-interrupted day of carnage Wednesday. Four of the eight seeds, including the second-ranked Peng Shuai, were sent packing in the second round with the world number 17 Peng beaten in straight sets 6-4, 6-3 by clay specialist Lucie Hradecka of the Czech Republic. Julia Goerges, Monica Niculescu and Roberta Vinci were the other seeds who had their Australian Open warm-up tournament brought to an abrupt end. Top seed Lisicki attributed her drawn-out match against fellow German Mona Barthel to fine-tuning aspects of her game. "We were working on a couple of things and I didn't go to the net at the right times sometimes," she said after her 7-6 (7/3), 3-6, 6-3 victory, which was stretched by a 90-minute rain break. "You sometimes have to sacrifice. I'm not perfect." Lisicki will meet another German, Angelique Kerber, in the quarter-finals after Kerber easily disposed of fifth seed Goerges 6-2, 6-3. Russian Elena Vesnina beat sixth-seeded Italian Vinci 6-3, 6-4 and will face another Italian, the enterprising fourth seed Falvia Pennetta. Pennetta breezed past Briton Elena Baltacha 6-4 6-2 and confidently said she "felt much better" than in the first round. Niculescu was tipped out of the second round 6-0, 6-2 by China's Zheng Jie. Third seed Svetlana Kuznetsova was the least troubled of the seeds in the second round as she thrashed American Christina McHale 6-1, 6-1.