Stanislas Wawrinka has claimed that Roger Federer will feel nervous heading into the pair's semi-final clash at the US Open because he is now on the 17-time Grand Slam champion's "level".

The 30-year-old, who has claimed three wins over Federer in his career, will take on his Swiss countryman on Friday after sealing a straight-sets victory over Kevin Anderson.

While Wawrinka has admitted that he will feel nervous heading into the showdown at Flushing Meadows, the two-time Grand Slam champion believes that Federer will be wary of his threat.

"I think now we [will] both [be] nervous when we enter the court," Wawrinka told reporters. "Before it was only me. I was nervous because I knew I wasn't at his level, for sure.

"Now, I think we can see that he was also nervous every time we play each other the past few years. That's a big difference because that show how much he knows that I can play at his level, how much he knows that I can try to play my game and not just try to react about what he's doing."

The other semi-final is between world number one Novak Djokovic and defending champion Marin Cilic.