Jamie Hampton secured the last semi-final spot at the ASB Classic by defeating Kiki Bertens 6-1 6-7 (5) 6-2 tonight.
Hampton, the only unseeded player to reach the semis, will face off against tournament favourite Agieszka Radwanska tomorrow.
The match was a high quality affair, Bertens fighting back in the second set to make Hampton work hard for the win.
The American was strong in the third set but will need to eradicate the patchy parts of her game if she is to seriously challenge for a spot in the final.
Earlier, world No. 4 Radwanska had little trouble dispatching Elena Vesnina 6-3 6-3 in a rain-affected quarter-final today.
Vesnina put in a good showing to lead 2-1 in the second set before the weather caused a 90 minute delay but Radwanska proved too clinical once play resumed.
With things locked up at 3-3 on serve, a bassline call went against Vesnina, before Radwanska clinched the win with a shot across court.
Third seed Yanina Wickmayer guaranteed her semi-final spot by defeating compatriot Kirsten Flipkens 6-3, 6-4.
The pair were tied up at 3-3 midway through the second set before light rain interrupted play three times.
Wickmayer claimed the win after the umpire over-ruled a line call, although replays clearly showed the ball was out, Flipkens clearly upset at the decision.
Wickmayer will meet Germany's Mona Barthel in the semi-final, who became the first player into the final four this afternoon, when she needed less than 45 minutes to overwhelm Swede Johanna Larsson, 6-2 6-1.
Ironically, it was Larsson that eliminated more fancied German Julia Goerges - seeded second - in Round Two yesterday.
Only three seeds - and no Kiwis - have survived into today's quarter-finals, with Radwanska needing barely an hour to breeze through her second-round encounter.
The draw really opened up for the Pole yesterday, with second seed Goerges disappearing from the opposite end of the draw and the last remaining seed - Kazahkstan's Yaroslava Shvedova (sixth) - exiting her half of the draw.
Hampton continued her role as the party pooper yesterday, ousting hometown favourite Marina Erakovic in straight sets, after dethroning defending champion Zheng Jie of China on Day One.
After bowing to Hampton in singles, Erakovic's long day got no better, when she and Briton Heather Watson - the doubles second seeds - fell to veteran Cara Black of Zimbabwe and Aussie Anastasia Rodionova in a super-set tiebreak late last night.
Top seeds Goerges and Shvedova remain on course for the doubles final, but will have an opportunity to regroup from their singles defeats with no match today.
ASB Classic - Order of play
3-Liga Dekmeijere (Latvia)/Megan Moulton-Levy (US) v Cara Black (Zimbabwe)/Anastasia Rodionova (Australia)
4-Jill Craybas (US)/Eleni Daniilidou (Greece) v Julie Coin
(FRA)/Marie-Eve Pelletier (Canada)