Andy Murray's frustration boiled over as his Dubai run came to an end in the quarter-finals with a 7-5 6-4 defeat by Russia's Nikolay Davydenko.
Murray's frustration got the better of him on more than one occasion
The opening set was nip and tuck until Murray lost serve in the 11th game to hand Davydenko the chance to go ahead.
The 20-year-old Briton was lucky to escape censure for a string of audible expletives, but he rallied to take a 3-0 early in the second set.
However, Davydenko responded superbly with two breaks to seal the match.
He will now face Feliciano Lopez in the semi-finals after the unseeded Spaniard secured a 6-4 6-3 win over compatriot David Ferrer, seeded fourth.
Andy Roddick secured the the surprise of the night, though, when he earned an impressive straight-sets win over Rafael Nadal.
"The way he was serving tonight, it's tough," said Nadal. "You feel a lot of pressure when you're serving."
The American sixth seed was at his very best in winning 7-6 (7-5) 6-2 against the world number two to set up a much-anticipated last four match against Novak Djokovic.
The Serbian was barely troubled as he cruised past Russian Igor Andreev 6-2 6-1.
Meanwhile, Davydenko had few words of comfort for Murray following his victory, saying: "I played well. If you are crazy, you can lose your match... If you are concentrated you can win every game."
Murray admitted he was frustrated at the chances he squandered against the Russian but added that he was pleased with his efforts in Dubai overall.
"I had a lot of chances. Early in the first set I had a couple of break points, and against someone like him, once he starts to get comfortable from the baseline, he's really tough to beat, " he said.
"You could do with getting a good start and I did that in the second set, but I played a bad game to lose my serve.
"I wasn't so disappointed the way I was hitting the ball. I was just disappointed I didn't take the chances that I had because I had quite a few.
"But I'm not terribly disappointed with the week as a whole.
"I got through a really tough match against Fernando Verdasco and obviously beat the world number one so there's nothing to get too down about."
After impressing against Roger Federer in the first round, Murray struggled past Verdasco and was once again below par against Davydenko.
I'm not terribly disappointed with the week as a whole
His serve, which had been the key against Federer, was second best against world number five Davydenko.
In the first set, the Russian landed 83% of his first serves compared to Murray's 59%.
Davydenko, who had lost two of his last three meetings with Murray, was also the more aggressive of the two.
While Murray stood behind the baseline, relying heavily on his speed around the court, Davydenko regularly stepped inside the line and took his shots early - forcing his opponent into mistakes.
It was no surprise when the 20-year-old Briton lost serve in the 11th game and though he engineered a chance to make it 6-6, another error saw Davydenko edge the opening set.
Murray was furious with himself but that did at least mean he began hitting with more aggression at the start of the second set, earning himself a 3-0 lead.
But Davydenko quickly recovered, breaking back before holding serve to make it 3-3 despite multiple break points againat him in the next.
Murray held at 5-3 to force Davydenko to serve out the match but the Russian held his nerve to book a semi-final spot.