Ailing Briton Andy Murray suffered another setback to his French Open preparations as he was ousted 6-7 6-3 6-2 by Richard Gasquet in the third round of the Rome Masters on Thursday.

The world number four, who continues to be troubled by a long-term back injury, dominated the first set tiebreak, but was made to pay for missing 15 of 17 break points as he lost to the 22nd ranked Frenchman in just under three hours.

Holder Novak Djokovic and Rafael Nadal, who he beat in last year's final, reached the last eight in contrasting fashion.

Djokovic demonstrated the art of smashing a racquet as he beat Argentina's Juan Monaco 4-6 6-2 6-3 while Nadal made light work of fellow Spaniard Marcel Granollers, winning 6-1 6-1.

Murray had reached the quarter-finals in Monte Carlo but pulled out of the Madrid Masters with a back injury before winning his opening match in Rome.

The Scot said his back had been a problem for several months and admitted it was a concern heading into the French Open, which begins on May 27.

"I don't really want to go into detail of what it is and what treatment I've had done, but I've had it a while, since December," Murray told a news conference.

"Since then there hasn't been that much time to take an extended break and now with the French Open, Wimbledon, Olympics and the U.S. Open to come, there's not much time to take a rest.

"But hopefully by the time the French Open comes around I'll be in peak condition. That's the goal."

SWIRLING WIND

The swirling wind and shadows across the court made life difficult for both men, but 16th seed Gasquet took his chances to set up a quarter-final with Spain's David Ferrer, the sixth seed winning 6-0 7-6 against Gilles Simon of France.

Djokovic mangled his racquet when he lost the first set against but from 2-1 down in the second set he reeled off 20 of 24 points to draw level before going on to victory.

"I hope the children watching don't do that," a smiling Djokovic said of his racquet-smashing. "But I show my emotions out there. That's who I am.

"I struggled with the wind today and I was a bit defensive and passive in the first set, but once I was more direct I started to play much better."

Nadal eased through against Granollers in one hour and 28 minutes, setting up a clash with seventh seed Tomas Berdych.

Third seed Roger Federer set up a clash with Italy's Andreas Seppi but only after something of a struggle against former world number one Juan Carlos Ferrero, winning 6-2 5-7 6-1.

In the women's event, it was a good day for the Williams sisters as Serena and Venus reached the quarter finals.

REMARKABLE COMEBACK

Ninth-seeded Serena, fresh from her victory in Madrid last weekend, crushed Anabel Medina Garrigues of Spain 6-3 6-1, while unseeded Venus upset fifth seed Sam Stosur 6-4 6-3.

Venus's victory puts her in line for a place in the U.S. Olympic team, a remarkable achievement in her comeback after she was diagnosed with Sjogren's Disease, which saps her energy, during last year's US Open.

"Seriously," she said, before doing a fist pump at her news conference. "I wouldn't have come back so soon but I needed the points to get in the Olympics.

"I probably wouldn't have come back before Wimbledon or maybe even after it. I need to win more but that's great."

Things are likely to get tougher for Venus, though, when she plays holder Maria Sharapova in the last eight.

The Russian saved six set points in the first set before beating former French Open champion Ana Ivanovic 7-6 6-3.

Wimbledon champion and fourth seed Petra Kvitova also advanced with a 6-2 5-7 6-2 victory over Sorana Cirstea while China's Li Na and Italian Flavia Pennetta both won through.

World number one Victoria Azarenka pulled out on Wednesday because of an injury to her right shoulder.