MIAMI: Roger Federer preserved dignity among the elite at the Miami Masters, earning a comfortable opening victory after world number three Andy Murray crashed out to unheralded Mardy Fish.

World number one and top seed Federer quietly dominated Nicolas Lapentti Saturday, vanquishing the Ecuadoran 6-3, 6-3 in 66 minutes.

But it was another story for Murray, who fell 6-4, 6-4 to the 101st-ranked Fish.

Federer is the sole survivor of the top three as Murray's early exit followed that of second-seeded Serbian Novak Djokovic on Friday.

Federer admitted that seeing Djokovic and Murray bow out before he had even taken the court had given him pause.

"It worries me as well, being the top seed, seeing high seeds fall out of the tournament. I haven't even started playing yet, and there's two big names out of the tournament already."

But Federer said a solid service game was all he needed to steady his nerves.

"I came through because I served very well. I had a good start into all my service games. I always knew I was going to have a couple of chances at least on the return games," said Federer, who needed only two breaks of Lapentti to earn his 12th victory of the season.

Federer lined up a third-round clash with Frenchman Florent Serra, a 6-3, 3-6, 6-2 winner over Spain's Albert Montanes.

Federer is beginning a bid for a third Miami title after winning here in 2005 and 2006.

Swedish fifth seed Robin Soderling, the French Open runner-up, progressed to the third round with a 7-6 (7/5), 6-0 win over Australian Peter Luczak.

Croatian number seven Marin Cilic accounted for Stephane Robert of France 6-3, 6-1.

Spain's 10th seed Fernando Verdasco saw off Israel's Dudi Sela 6-1, 6-2 while 13th-seeded Russian Mikhail Youzhny eased past Santiago Giraldo of Colombia 6-0, 6-1.

Murray, the defending champion, looked to be sleepwalking through his 90-minute match in a city which he uses as a second home.

The defeat came in the wake of the Scot's contention that training in the brutal South Florida heat would be key to a possible title repeat.

Whatever Murray's problems on the day, Fish was delighted with the victory.

"He's a grand slam finalist (Australia) this year already, his results speak fo themselves," said the winner. "It's a great win.

"I certainly had to serve well, and I did when I needed to. Got me out of some jams there late in the match.

"He certainly didn't play the way he did in Australia or something - but I don't care."

Murray admitted he has work to do on his game.

"Mardy served well when he needed to, especially the second set when he was down break points," said Murray. "I just wasn't very good today, and I'm going to need to get a lot better."

Fish struck 10 aces and went for his shots with 33 winners and 41 unforced errors.

Murray managed just 12 winners and 23 errors and converted only one of five break point chances.

"Last week was poor, too," said Murray, who went out in the quarter-finals of the Indian Wells Masters 1000. "It has not been great since Australia.

"I need to find a way to get round it, and I'm sure I will. I've gone through bad patches before, and I just need to practise hard, work hard, and get stronger. I'm sure I'll start playing better again."

In the women's WTA event, top seed and 2006 winner Svetlana Kuznetsova beat Agnes Szavay of Hungary 6-2, 6-3 to reach the fourth round.

Three-time champion Venus Williams improved her own record at the Miami event with a 6-1, 6-4 victory.

The American, who lifted the title at Crandon Park in 1998, 1999 and 2001, claimed her 12th consecutive match win after back-to-back titles in Dubai and Acapulco this season.

The third-seeded Williams fired six aces in her 70-minute win, but also produced seven double-faults.

"Obviously being on a winning streak helps my confidence every time," said Williams, the last remaining American in the women's draw.

Poland's sixth seed Agnieszka Radwanska ended the comeback hopes of former number one Ana Ivanovic 7-5, 7-5 as the Serb struggles to regroup under new Swiss coach Heinz Gunthardt.