Indian Wells, California  - Defending champion Novak Djokovic continued to rebuild his fragile confidence with a 7-5, 6-4 win over Argentine Marcel Vassallo Arguello to move into the third round of the Indian Wells Masters on Sunday.

"This year hasn't started maybe the way I thought I would, but now I've raised my confidence in a higher level," said the 2008 Australian Open champion who won his first title of this season a fortnight ago in Dubai.

"Winning there meant a lot for my confidence level and for my game overall."

Third seed Djokovic broke three times in his win over Vassallo Arguello in an hour and three-quarters, saving both of the break points he faced.

"Winning this first match, it's never easy, I played against a solid opponent," said the Serb who beat Mardy Fish for the 2008 title. "He made me work from the baseline. But I played as much as I needed to, and I'm happy to get through."

Fish was not so lucky, hooked by up-and-coming Frenchman Jeremy Chardy 7-6 (7-4), 7-6 (7-1), the number 48 who lost to the American in the Delray semi-finals late last month.

"The kid's good, it was a terrible draw for me," lamented Fish, who beat Roger Federer in semi-finals in the desert a year ago. "I played extremely well last week in the semis against him.

"I won 10 of the last 12 games against him there. But he certainly played a lot better. He served a ton better today and didn't give me very many break points."

Argentine sixth seed Juan Del Potro opened with a victory over American Ryan Sweeting 6-7 (6-8), 6-3, 6-1, while Spanish 12th seed David Ferrer eliminated another countryman in Todd Widom 6-4, 7-5.

The US lost a third minor player as Nicolas Kiefer dispatched Bobby Reynolds 6-4, 6-2. Swiss 16th seed Stan Wawrinka beat Italian Andreas Seppi 6-1, 6-3.

On the women's side, Russian fourth seed Vera Zvonareva reached the fourth round over Petra Kvitova 6-3, 6-1, while Danish ninth seed Caroline Wozniacki stopped fellow north European Kaia Kanepi of Estonia 6-3, 3-6, 6-3. (dpa)