MELBOURNE -- World No. 3 Novak Djokovic and U.S. Open champion Juan Martin del Potro kicked off their Australian Open preparations with easy first-round wins at the Kooyong Classic in Melbourne on Wednesday.
Despite blustery conditions at the Kooyong Lawn Tennis Club, del Potro was in fine touch for his first hit-out of the season, although he may hope for tougher encounters this week after Ljubicic repeatedly gifted him key points with unforced errors.
"The weather conditions were tough, a lot of wind," del Potro said. "I returned very good, I served very good so that's important for this kind of match, this kind of surface. It's a good victory in the beginning of the season, of course."
After breaking the 24th-ranked Croat in the opening game, del Potro cracked two forehand winners to set up two set points at 5-3 and was handed the set when his opponent double-faulted.
Ljubicic raised his game after conceding an early break in the second, clubbing three aces in a row to save two match points at 5-2 before getting a break-back point in the following game.
The towering Argentine, however, held serve with an ace and sealed the win on his fourth match point after the Croat netted a forehand.
The 30-year-old Ljubicic, who took Roger Federer's place after the world No. 1 elected to skip his usual Australian Open warm-up, was philosophical about the loss despite spending most of the time between points frowning with his head bowed.
"It wasn't all that bad actually. Probably the most disappointing thing is that I didn't feel bad at all and I still lost 6-3, 6-3," he said. "Definitely, I will have to still improve with each match here.
Djokovic, the 2008 Australian Open champion, raced to a one-set lead after breaking 18th-ranked Haas early and carried the momentum into the second in a controlled display.