Hantuchova claimed conditions at the WTA International event on Wednesday - when she beat Zhang Ling in straight sets - were "probably the toughest" she had ever played in.
The Russian also said she was "really struggling with the heat" in her win and it did not surprise when she ran out of steam against Belgian Alison Van Uytvanck one day later.
Van Uytvanck came from behind to win the second-round clash 3-6 6-2 6-4 in two hours and 19 minutes.
The 20-year-old recovered well from her slow start, making two breaks in each of the second and third sets at the hard-court event to progress to the quarter-finals.
The Belgian will play Australian Jarmila Gajdosova in the last eight.
Third seed Karolina Pliskova had more joy, with the Czech toppling Puerto Rico's Monica Puig 6-3 6-4.
Puig struggled on serve and 10 double-faults helped Pliskova make four breaks in her comfortable win.
Next up for Pliskova is a clash with China's Jie Zheng, who cruised past Kai-Lin Zhang 6-1 6-4.
Jana Cepelova - also of the Czech Republic - was too good for Chinese qualifier Lin Zhu, winning 6-1 6-3.
She will play Italian Francesca Schiavone next, while the other quarter-final sees top seed Sabine Lisicki meet Saisai Zheng.
Lisicki lost just 17 points against Grace Min in a 6-1 6-1 demolition on Tuesday.