Top-seeded Agnieszka Radwanska beat Russia's Elena Vesnina 6-3, 6-3 after a lengthy rain delay Thursday to advance to semifinals of the ASB Classic.
The fourth-ranked Pole kept her composure after the players were forced off the court early in the second set, returning to close out her third straight-set win of the tournament.
Radwanska was joined in the semifinals by the two other seeded players remaining in the draw. Third-seeded Yanina Wickmayer of Belgium beat countrywoman Kirsten Flipkens 6-3, 6-4 and eighth-seeded Mona Barthel of Germany beat Sweden's Johanna Larsson 6-2, 6-1.
American Jamie Hampton, who upset defending champion Zheng Jie of China in the first round, also advanced with a 6-1, 6-7 (5), 6-2 win over Kiki Bertens of the Netherlands.
Hampton took the first set in 28 minutes and broke Bertens in the first game of the second set before the Dutch player regrouped to break back and level the match.
The American then broke Bertens in the second and fourth games of the deciding set to prevail in just over two hours.
Wickmayer will play Barthel in Friday's semifinals and Radwanska will play Hampton.
Vesnina led 2-1 in the second set when the rain came and stopped play for nearly two hours. When the players returned, Radwanska broke her Russian opponent in the seventh game to finish off the set and match.
"I knew that against her I would have to play very well from the first point to the last and fortunately, in both sets, I was able to play my best tennis,'' she said.
Wickmayer also had to deal with the rain to beat Flipkens, her Fed Cup teammate. There were three short rain delays during the match, but Wickmayer, the 2010 Auckland champion, stayed in charge throughout.
"I guess it was a little tougher than a normal match,'' she said. "We know each other really well, we've shared a lot of good moments in the Fed Cup.''