World number one Rafael Nadal [ Images ] was handed a walkover into the quarter-finals of the Madrid Open on Thursday when his third-round opponent Philipp Kohlschreiber was forced out of the claycourt event with a left leg injury.

Nadal was joined in the last eight by world number two Roger Federer [ Images ], a 6-2, 6-4 winner over James Blake [ Images ], and Andy Murray [ Images ], who coped well with blustery conditions in the Magic Box stadium to dispatch Spanish 16th seed Tommy Robredo [ Images ] 7-5, 6-1.

Serbia's Novak Djokovic [ Images ], chasing a fifth straight final appearance, also advanced with a routine 6-4, 6-4 victory over unseeded Italian Andreas Seppi.

Fans waiting to see local hero Nadal play Kohlschreiber on centre court were handed a disappointment around three hours before the match was due to begin when the ATP announced the German had withdrawn.

The Mallorca native is bidding for a sixth title of the season and a fourth on clay and will play seventh-seeded compatriot Fernando Verdasco [ Images ] for a place in the last four.

CRASHING RETURN

Federer fell to Blake at last year's Beijing [ Images ] Olympics [ Images ] and laid down a marker in the opening game against the American 14th seed, breaking serve with a crashing backhand return.

The 13-times Grand Slam winner, who has yet to win a title this year, wrapped up victory with a fifth ace on his first match point and will play Andy Roddick [ Images ] in the next round.

The sixth-seeded American was also given a walkover when his opponent Nikolay Davydenko [ Images ] withdrew with a left leg injury.

"I didn't really see it as a revenge match," Federer said of the Blake clash. "The tennis wasn't as good as in Beijing but I'm happy it was that easy. It was a solid performance."

A single break of the Robredo serve in the 11th game of a tight first set and three more in the second were enough to seal a comfortable win for world number three Murray and he converted his first match point with a backhand return down the line.

The Briton, who turns 22 on Friday, has never won a tour title on clay and is looking to improve his record on the surface ahead of the French Open [ Images ] which starts later this month.

He will next play Juan Martin Del Potro [ Images ] after the Argentine fifth seed battled past 11th-seeded Swiss Stanislas Wawrinka 4-6, 6-4, 6-4.

"It was tough from one end where the wind was blowing right into your face and Tommy was dictating a lot of points from that end in the first set," Murray told a news conference.

"I was just a little bit tense when I had my chances. I had a lot in the first set and didn't take them and played a little too passive.

"The second set was much better and I started to dictate a lot of the points."

World number four Djokovic had a reasonably smooth passage against Seppi to set up a last-eight clash against wildcard Ivan Ljubicic, who battled back from a set down to beat eighth seed Gilles Simon 3-6, 6-4, 6-3.

"I wish I'd had a withdrawal," Djokovic said at a news conference. "As it was I had to work very hard."