Nicolay Davydenko will meet Roger Federer in the semifinal of the US Open after the Russian number one's amazing comeback against Tommy Haas.

The German didn't seem very tired after the five set battle with Marat Safin the day before.

After taking the first set 6-4, Haas looked well on his way to his first US Open semi when he took the second in a tie-break.

But then Davydenko broke Haas's serve once in each of the third and fourth sets to level the match.

The 7th seed went 5-2 up in the decider, but Haas fought back and found himself within a game at 5-4.

Davydenko didn't let the victory slip away from his hands though and joined Mikhail Youzhny in the semis.

It's going to be only the second time in the Open era that two Russians are in the last four.

Marat Safin and Evgeny Kafelnikov made it to the semis in 2001.