Djokovic, Nadal, Federer into last eight, Murray out in Rome

Novak Djokovic, Rafael Nadal, and Roger Federer reached the Rome Masters quarterfinals on Thursday, but fourth seed Andy Murray suffered another setback in his French Open plans when he crashed out to Richard Gasquet.

Murray, who lost 6-7 (1/7), 6-3, 6-2 to the Frenchman, revealed that he has been carrying a back problem since December, but declined to go into details on the symptoms or its treatment.

However, he did admit to facing a race against time with the French Open starting in Paris a week on Sunday.

"I've felt it for some months, but I haven't had a chance to take a pause. I've tried not to make it any worse, but the muscles get tired from compensating," said Murray, who skipped last week's Madrid Masters because of the problem.

"I've got a lot of big events coming and there's not that much time to rest any niggles. Hopefully when the French comes, the goal is to be in peak condition."

Top seed Djokovic, the defending champion, staged a 4-6, 6-2, 6-3 comeback win over Argentine Juan Monaco, while second seeded Nadal was ruthless with fellow Spaniard Marcel Granollers, winning 6-1, 6-1.

Djokovic will tackle Jo-Wilfried Tsonga, who saw off Juan Martin Del Potro 6-4, 6-1, for a place in the last four.

"Conditions were very difficult for us. I finally settled into the match," said Nadal, who will next face Tomas Berdych after last week's Madrid finalist beat Spain's Nicolas Almagro 7-6 (7/3), 6-3.

Federer, the winner of the Madrid Masters, defeated fellow veteran and former world number one Juan Carlos Ferrero 6-2, 5-7, 6-1 with a dozen aces and four breaks of serve.

The Spaniard took the clash to a third set with a late break before the third-seeded Swiss set-up a last-eight match with Italy's Andreas Seppi who saved six match points in a 6-7 (1/7), 7-6 (8/6), 7-6 (8/6) win over Stanislas Wawrinka.

Federer improved to 47-3 since last year's U.S. Open semifinals, winning seven of his past 10 tournaments and returning to number two in the world.

Spanish sixth seed David Ferrer knocked out French 11th seed Gilles Simon 6-0, 7-6 (7/5) and will tackle Gasquet.

With gusts of wind making life a challenge in all matches, Djokovic had to smash a racquet to bits to get himself motivated after losing the opening set to Monaco.

The outburst came after the Argentine had finally converted a fifth set point in the blustery conditions.

The Serb went down a break in the second set, but got it back and then broke again to level the match at a set apiece.

It took a break for 5-3 in the final set to put Djokovic into position to close out victory on his second match point.

"It was difficult to play in the wind, but it was the same for both of us," said Djokovic.

"He was able to deal with the conditions better at the start, but after a set and a half I started to play better and change my strategy.

"I never expected an easy match against him on his favorite surface. I felt I started hitting the ball better. I found my rhythm."

In the women's event, world number one Victoria Azarenka withdrew before her match against Dominika Cibulkova with a right shoulder injury while defending champion Maria Sharapova beat Ana Ivanovic 7-6 (7/4), 6-3.

Wimbledon champion Petra Kvitova, the fourth seed, stopped Sorana Cirstea 6-2, 5-7, 6-2.

Madrid winner Serena Williams, the ninth seed, advanced over Anabel Medina Garrigues, 6-3, 6-1.

The American admitted that while she is aiming to win Rome for the first time in a decade, she is well into the countdown for Roland Garros.

"I'm getting nervous. I feel good and I've had a lot of practice on clay," she said.

"Today I was running so much, I was ready to play and feeling good. I wasn't tired at all."

Sister Venus knocked out U.S. Open champion, and fifth seed, Samantha Stosur 6-4, 6-3 and will face Sharapova on Friday.