Roger Federer's defence of the Dubai Open title came to a dramatic end in the semi-finals after he failed to convert three match points against Tomas Berdych, the man who also upset him in the US Open.
The world number six from the Czech Republic thrillingly turned the match around after a neck-and-neck second set tie-break, going on to win 3-6, 7-6 (10-8), 6-4 against the five-time champion and set up a final against Novak Djokovic.
The Serbian world number one extended his unbeaten run to 17 matches and reached the 55th final of his career with a 6-3, 7-6 (7-4) win over Juan Martin Del Potro, the former US Open champion from Argentina.
Federer was on the verge of success at 6-4 and 8-7 in the tie break, with the second of the three points coming on his serve, only for Berdych to somehow get into a rally and win it with some fierce ground strokes.
One break of serve halfway through the final set then proved decisive, as Federer gambled more and more on rushing the net instead of continuing the bruising baseline exchanges which characterised the first two sets.
"It's obviously unfortunate, you know," said Federer, for whom this is a tournament in his second home. "Pity to lose that one, but Tomas did well to hang in there.
"Obviously I leave this match with a lot of regrets I'm feeling: serving for the match, with the serve, having chances in the beginning of the second, you know, when he wasn't quite in the match yet, to go break up, you know, set and a break, you know, a few points where things just didn't happen for me."
Of his best chance, the second match point, Federer said: "That's just disappointing right there, because the match was in my racket.
"You do all the right things for so long, and then at the end you've got to explain why you didn't hit two shots decent, you know. So it's disappointing."
Berdych was pleased that he avoided the perils of tension in the later stages, as he closed the match out.
"Staying calm is definitely the big thing I have been working on," he said. "And I am still working on it, especially with the serve. When I serve well I can do a lot of damage."
Earlier, Djokovic was again in fine fettle for a man who had not played a tournament since the successful defence of the Australian title nearly five weeks ago, and, after three solid wins already, he raised his level once more.
Djokovic was made to.
Del Potro hit fierce first serves and heavy ground strokes mixed in with thunderbolt accelerations with his forehand, advancing to a 3-0 lead in the second set.
Djokovic responded superbly when behind, containing brilliantly, moving superbly, and counter-attacking with excellent timing and accuracy.
However, his break back to 2-3 came amidst controversy. Umpire Magdi Somat imposed a time violation on Del Potro when he took a longer to prepare at a vital moment, at 30-40, break point down.
The Argentine walked up to the umpire to protest, gesticulating as he did so, and accompanied by a spate of boos from spectators. By the time the situation had calmed, the delay was at least twice the permitted 25 seconds.
There followed a forehand-to-forehand exchange ending with a mishit under pressure by Del Potro costing him the game. When they sat down at the change of ends there was another exchange between the umpire and Del Potro, with further jeering from spectators.
Djokovic was critical. "I don't know exactly if the chair umpire gave him unofficial verbal warning before that. If he didn't, then I don't agree with that decision," he said.
It muddied the waters and proved to be a turning point. It also landed the Argentine with extra pressure in his next service game and although he diligently saved two break points amidst a sequence of excellent rallies, Djokovic eventually broke serve.
"It was very important point for the game, for the match," Del Potro said of the timing of the umpire's decision. "Maybe he doesn't know about that, you know.
"I mean, in that moment, if you call warning or if you do something different, you can lose the focus and that's what happened with me."