Djokovic's fellow Serb Janko Tipsarevic outlasted Murray in a two- and-a-half-hour struggle 7-6 (7-3), 4-6, 6-4 after the Scot saved a match point in the penultimate game.

German Michael Berrer put an end to injured Davydenko's quest, the Russian quitting with an existing wrist problem to hand over a 6-3 victory in 45 minutes.

Second seed Djokovic was hardly pleased by his performance.

"I wasn't happy with the performance overall today," confessed the world number two. "But I won, that's what matters. He was a better player for a set and a half.

"This is one of the rare tournaments that you really feel big, big difference between the day match and night match. The balls go really much faster, and as soon as the shade came on the court, you know, I felt more control over my game.

"In the end, I managed to win," Djokovic said.

Murray and Tipsarevic battled in a strategic contest, with the result turning on a few points in the tight final set. Both men hit 13 aces and each saved three break points as number 39 Tipsarevic reversed two losses to the Scot.

"My main goal was to focus on my game and keep calm," said the Serb. "If you don't stay calm against Andy he will break your serve every time.

"I made sure I did not get frustrated and took my chances when I could. I'm really tired, as I'm playing both singles and doubles tomorrow. We will have to see how it goes."

Murray's defeat came less than a month after he lost the Australian Open final to Roger Federer. But the Scot never looked at his best this week, coming to Dubai after barely practising since Melbourne.

He said that he used the match to "try some things," with few regrets in defeat.

"It's disappointing to lose, but it's not the end of the world. I was not well-trained coming into Dubai. I was trying some things and made more mistakes than usual. I'm happy though with how I fought."

Tipsarevic next faces Russian Mikhail Youzhny, who beat German qualifier Bjorn Phau 7-6 (7-2), 6-4.

Jurgen Melzer of Austria, Cilic's next opponent, got past Tommy Robredo 6-3, 7-5 to reach a third quarter-final in four 2010 events.

Marcos Baghdatis of Cyprus, def. Samdev Devvarmen, India, 6-3, 3- 6, 6-1

Davydenko had never looked like making a run after falling on the wrist during a Rotterdam semi-final earlier this month. He had not even been sure of playing.

"I started to have more pain during the match. It was too much for me, it was risky and it was better to retire," he said.

Marin Cilic, seeded sixth, continued his smooth passage, reaching the last eight in less than 90 minutes over Austrian Stefan Koubek 6- 2, 7-6 (8-6).

"I let my game drop a little bit in the second set," said the Croatian with two titles already this season. "Overall I played pretty good today - smart and aggressive when I had to be."