South Africa's Kevin Anderson pulled off the biggest upset so far at Indian Wells on Saturday, ousting fourth-seeded Spaniard David Ferrer 3-6, 6-4, 6-3 in the second round.

Ferrer, ranked fourth in the world, was playing his first match of the combined ATP Masters and WTA Tournament, in which the 32 men's and women's seeds receive first-round byes.

Roger Federer and Victoria Azarenka were both slated to launch their title defenses with second-round matches later Saturday.

Federer, the second seed behind world No. 1 Novak Djokovic, was to face Uzbekistan's Denis Istomin and women's top seed Azarenka was set to take on two-time Indian Wells champion Daniela Hantuchova.

Fifth-seeded Spaniard Rafael Nadal, playing his fourth tournament after a seven-month injury absence and his first hard court tournament since injury forced him out of the Miami Masters last March, faced a second-round opener against American Ryan Harrison.

Nadal launched his comeback from a left knee injury with three clay court tournaments in Latin America.

He reached the final in the first and won the next two, including an impressive victory in the Acapulco final last Sunday over Ferrer.

Ferrer said he expected Nadal to flourish on hard courts, just as he has on clay.

"I think Rafael is coming back up," Ferrer said. "I played with him on a clay court. It was a different court, but he's playing good. He's not playing with pain in his knee and that is a very good point."

For his own part, Ferrer said the 37th-ranked Anderson just played better.

"He played good in important moments," said Ferrer, who was unable to convert two break opportunities in the ninth game of the second set.

"He played more aggressive, more consistent than me. And in the third set I was a little bit tired and he was better than me."

In the third round, Anderson will face Jarkko Nieminen. The 31-year-old Finn ranked 57th in the world ousted another seeded Spaniard, 29th-ranked Fernando Verdasco, by 6-1, 6-0.

In early women's matches, Germany's fourth-seeded Angelique Kerber reached the third round with a 6-3, 6-2 victory over Romanian Irina-Camelia Begu.

Seventh-seeded Australian Samantha Stosur used a break of serve in each set to dispatch US teenager Madison Keys 6-3, 6-4.

Stosur, the 2011 US Open champion, next faces China's Peng Shuai, who defeated Romanian Alexandra Dulgheru 6-0, 4-6, 6-3.