Top-seeded Ivan Ljubicic led five Croats into the second round of the PBZ Zagreb Indoors with only countryman and second-seeded Ivo Karlovic losing his opener on Tuesday in Croatia.
Ljubicic, the 2006 champion and 2007 runner-up, hit 13 aces and broke serve only once in beating Ernests Gulbis of Latvia 6-3, 7-6 (7).
DUBAI, United Arab Emirates Sixth-ranked Anna Chakvetadze ended a two-match losing streak by beating Agnieszka Radwanska 6-2, 2-6, 6-4 in the first round of the Dubai Championships on Tuesday.
Also advancing were Amelie Mauresmo of France, Sania Mirza of India and Francesca Schiavone of Italy. Australian Open champion Maria Sharapova withdrew with a viral illness.