Russian Nikolay Davydenko dumped Andy Murray out of the Dubai Championships in the quarter-finals with a 7-5 6-4 victory over the British number one.

The fifth seeded Davydenko will face Feliciano Lopez in the last four after the Spaniard beat compatriot David Ferrer 6-4 6-3 earlier on Thursday.

Murray had beaten Davydneko just two months ago on his way to the Doha Open title, but the 20-year-old Scot put in his second consecutive sluggish outing after stunning world number one Roger Federer in the first round.

Though the two were essentially even for most of the first set, Davydenko earned the critical break in the 11th game before easily sealing the opener on his serve.

Murray struck back with a quickfire break of serve to build a 3-0 lead in the second set, but then seemed to collapse mentally as Davydenko reeled off five consecutive games including two breaks of serve.

Despite hitting four double faults over the course of the match, Davydenko easily closed out the victory with a love-service game in the tenth game of the second set.

Andy Roddick did not appear to be missing the services of a coach during his 7-6 6-2 quarter-final victory over Spanish second seed Rafael Nadal.

The sixth-seeded American, who said he had parted ways with his coach Jimmy Connors, will next face third seed Novak Djokovic after the Serbian swept aside Russia's Igor Andreev 6-2 6-1.

Roddick placed Nadal under pressure from the start, holding serve with the first of his 17 aces and then forced Nadal to save four break points to level at 1-1.

With both players refusing to cave in and saving numerous break points, the set headed into a tiebreak.

Nadal swiftly took a 3-0 lead but Roddick fired two successive aces to keep pace and eventually claimed it 7-5.

"I felt I was getting the best of him throughout the set, and then all of a sudden I'm down 3-0 in the tiebreaker pretty quick and that was a little discouraging," said Roddick.

Roddick surprisingly faced little resistance in the second. Nadal began to make far more errors and after Roddick broke twice to lead 4-1.

A 241 kph ace set up match point and he closed it with yet another ace.

"It's a fast court, the crowd was really into it and the atmosphere was great. I wasn't going to get better conditions for myself against Rafa. I knew that and tried to take advantage," said the former world number one.

Nadal admitted that Roddick's powerful serve had put his own game under pressure.

"You feel a lot of pressure when you are serving because if you lose any serve, the way he was serving tonight it's tough," said Nadal.

"But in a way I am not disappointed with my game tonight. I didn't play badly."

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