Calleri made three unforced errors in the first-set tiebreaker and lost his service twice in the second set.

``I am very happy that I played well,'' Ljubicic said. ``I felt some pressure coming back to Vienna as the titleholder but things went well in the second set.''

Ljubicic, the No. 1 seed, will play Florian Mayer of Germany in the second round.

Second-seeded David Nalbandian also advanced after beating fellow Argentine Juan Ignacio Chela 6-7 (6), 6-2, 6-2.

Nalbandian, who led 5-3 before wasting two set points in the tiebreaker, hit 27 baseline winners in his first match since his second-round exit at the U.S. Open last month.

``It's hard for me to play Juan Ignacio. We train a lot together, so he knows my game very well,'' Nalbandian said. ``I played well in the second and third set. The rather slow surface worked in my favour.''

Also, fourth-seeded Marcos Baghdatis of Cyprus advanced after beating Spain's Ruben Ramirez Hidalgo 6-3, 3-6, 6-4. Baghdatis needed medical treatment for muscle cramps in his right forearm twice in the final set, but then broke his opponent two times to complete the victory in two hours 22 minutes.

Spain's Carlos Moya beat compatriot Nicolas Almagro 3-6, 6-3, 7-6 (3), though Almagro had 16 aces and lost his serve only once.

Qualifier Lukasz Kubot of Poland defeated Sebastien Grosjean of France 6-4, 6-3.

Wild card Stefan Koubek of Austria went through to the second round after downing Germany's Denis Gremelmayr 6-1, 6-0 in less than 44 minutes.

Also, sixth-seeded Tommy Haas of Germany defeated wild card Martin Fischer of Austria 7-6 (3), 6-2.