Germany's Tommy Haas saved a match point as he battled into the Australian Open semi-finals with a five-set win over third seed Nikolay Davydenko.
Haas is through to the semis in Melbourne for the third time
Haas, seeded 12th, won 6-3 2-6 1-6 6-1 7-5 in three hours 19 minutes and will play second seed Rafael Nadal or 10th seed Fernando Gonzalez in the semis.
"That's one of my best wins, being down a break in the fifth," said Haas, who saved a match point at 4-5.
"I don't know how I did it, I was just hanging tough. I'm so happy right now."
Davydenko looked on course for victory when he moved two-sets-to-one in front but Haas swept through the fourth to set up a tense decider.
It's one of my biggest matches I've won, for sure
The decisive moment seemed to have arrived in game 10 when Davydenko had a match point on Haas's serve, but he buried a forehand into the net.
Haas then played a superb game to break but there was more drama on the German's first match point in game 12.
Davydenko's return was called out but he successfully challenged thanks to Hawk-Eye, before Haas put his vociferous supporters out of their misery by taking his second match point.
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The 28-year-old German will now play in his third Australian Open semi-final, having lost to Yevgeny Kafelnikov in 1999 and Marat Safin in 2002.
"It's one of my biggest matches I've won, for sure," said Haas.
"In the quarter-finals, to save a match point, the number three player in the world, I've never beaten him before, coming back from a break down, match-point down.
"Another reason why I'm really happy is now I finally beat a Russian in a big match here. I lost to (Yevgeny) Kafelnikov and to Marat (Safin) in the semis here.
"If I would have lost the quarter-final here against another Russian, it would have been really like never going back there again."
Davydenko said: "I put no pressure on him. He made all the pressure. That's why he won in the five sets."