Mikhail Youzhny is in the US Open semi-final after taking over four hours to struggle past Stanislas Wawrinka in the quarters on Thursday.

Russian Youzhny triumphed 3-6 7-6 (9-7) 3-6 6-3 6-3 after an error strewn marathon with his 25th seed Swiss opponent at Flushing Meadows.

Wawrinka dispensed with one of the tournament favourites Andy Murray back in the third round, but he couldn't find a way past Youzhny, who will now face the winner of the last quarter-final between world No.1 Rafael Nadal and Fernando Verdasco.

"I like New York. I like to play here," Youzhny said. "It was really tough, but now I'm happy."

Wawrinka fluctuated throughout the match, taking the first set comfortably before succumbing to Youzhny in a tie break to lose the second.

The Swiss smashed 13 aces past Youzhny and hit 13 more winners than the Russian, but was ultimately undone by 71 unforced errors.

Youzhny clung on as Wawrinka took a 2-1 lead after the third, but the Russian battled the strong gusts that have become a feature of the tournament to claw his way back into contention and take the fourth.

"There were breaks in the first, breaks in the second. It was tough conditions because of the wind; you never know what's going to happen," Youzhny said.

Wawrinka faded visibly late on, perhaps feeling the effects of successive gruelling encounters with Murray and Sam Querrey in the third and fourth rounds, the Swiss required treatment for a thigh problem in both matches.

Youzhny took advantage of Wawrinka's dip in intensity late on, breaking serve in the fifth and ninth games of the decider to earn his semi-final berth.