Hantuchova came from behind in eliminating Aravane Rezai 4-6, 6-1, 6-2 in the opening day of the clay-court tournament.
Also Monday, 10th-seeded Elena Dementieva had little trouble in ousting Maria Elena Camerin 6-1, 6-2, and No. 11 Shahar Peer hadn't lost a game and led 6-0, 2-0, when Agnieszka Radwanska retired with a right wrist injury.
The top seeds for the Italian Masters are No. 1 Amelie Mauresmo and second-seeded Svetlana Kuznetsova.
Martina Hingis, out with an injury, won last year's tournament but is not defending her title.
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