MIAMI, Florida: Rafael Nadal joined Roger Federer as a seeded survivor at the upset-plagued Miami Masters as the Spaniard defeated David Nalbandian 6-7 (8/10), 6-2, 6-2 Sunday for a fourth-round berth.

Top seed Federer and number four Nadal are all that are left of the top four seeds after exits by number two Novak Djokovic and number three Andy Murray in the second round.

American sixth seed Andy Roddick kept the home crowd happy with his 6-2, 6-1 defeat of Sergiy Stakhovsky of the Ukraine, while resurgent Spanish veteran Juan Carlos Ferrero eliminated John Isner of the United States 6-2, 3-6, 6-3.

Nadal's next opponent will be 15th seeded compatriot David Ferrer, who tamed the huge serve of Ivo Karlovic - only ten aces for the Croatian - 7-6 (7/5), 6-3.

Fellow Spaniard Nicolas Almagro beat Frenchman Jeremy Chardy 6-2, 6-7 (9/11), 6-3 to set up a match with Brazil's Tomaz Bellicci, who ended the run of Djokivic's conqueror Olivier Rochus of Belgium 6-3, 6-4.

Nadal, who won his last title last May in Rome, is not fussed about his lack of recent trophy success. Instead, he's looking for small improvements as he gets back in the groove in the wake of the knee injury suffered at the Australian Open.

"I'm in the fourth round for me," he said, refusing to consider the potential organiser's dream Federer-Nadal title match. "It's far away from that moment.

"It's an important win for me today and I'm very happy for that. I'm pleased with how I'm doing in this American hardcourt season. Every match right is really important for me, and every victory gives me confidence."

Argentina's Nalbandian is finding his way again after last year's hip operation and a recovery setback in the form of an abdominal strain in January.

He had won two of the pair's three previous matches, but Nadal prevailed in their last encounter in the fourth round of Indian Wells in 2009 - saving five match points along the way.

"I'm very happy to see him back after an important surgery," said Nadal. "He's a close friend of mine and he's a talent.

"He can make very difficult things very easy. When he's playing at his best level he makes you feel like you are nothing in the middle of the court."

In women's WTA play, second seeded US Open finalist Caroline Wozniacki battled through illness to defeat Maria Kirilenko 1-6, 6-1, 6-4.

"I felt dizzy from the middle of the first set already," said the Dane. "Even though I didn't feel 100 percent, I still went out there and fought. The third set I started to feel better. I think everything started to get to normal almost, and I felt much better.

Victoria Azarenka, the defending champion, continued her quest for a second title with a 6-4, 6-2 defeat of Lucie Safarova.

Indian Wells winner Jelena Jankovic, seeded seventh, moved past Russian Elena Vesnina 7-6 (7/3), 6-3.

Ninth-seeded French Open semi-finalist Samantha Stosur of Australia produced a second consecutive comeback from a set down as she defeated Virginie Razzanoof France 4-6, 7-5, 6-1.

Russian 11th seed Vera Zvonareva eliminated Sara Errani 6-2, 6-3 and another Russian, Anastasia Pavlyuchenkova, beat Errani's Italian compatriot Francesca Schiavone 7-5, 6-3.

US Open winner Kim Clijsters, seeded 14th, re-established normal service in a hammering of Israeli Shahar Peer 6-0, 6-1. The Belgian won nine games in a row and needed just 50 minutes.

Clijsters was upset in the third round of Indian Wells but said she's back on her game after two wins this week in Florida.

"It's nice to have a feeling where your brain and your arm is kind of connecting," joked the mother of one. "In Indian Wells it was a completely different story."