Hantuchova needed more than two and a half hours to edge past Melinda Czink in the previous round and perhaps paid the price for that against New Zealand's Marina Erakovic.
Erakovic won 6-4 6-4 to advance to the semi-finals, where she will face third seed Tamira Paszek.
Paszek won a hard-fought clash with British teenager Heather Watson, the Austrian prevailing 6-4 7-6 (7/5) in a match lasting two hours and seven minutes.
The other semi-final will see Holland's Michaella Krajicek take on sixth seed Barbora Zahlavova Strycova.
Krajicek beat Canada's fourth seed Rebecca Marino 6-1 6-3 in the quarter-finals, while Strycova overcame fellow Czech player Andrea Hlavackova 6-3 7-5.