New York: Stan Wawrinka believes he is one of the few players that makes Roger Federer nervous as the Swiss duo prepare to do battle in the US Open semi-finals.

Federer is yet to drop a set in five matches at Flushing Meadows, where he has continued his recent renaissance with a series of dazzling displays.

Stanislas Wawrinka returns to South Africa’s Kevin Anderson during their US Open quarter-finals. Pic/AFP

Richard Gasquet was the latest opponent to be blown away on Thursday and of the four men left in New York, Federer now tops the tournament table for winners (26 per cent), return winners (15), first serves in (65 per cent) and service games won (97 per cent).

Aged 34, and the oldest player left in either the men or women’s competitions, even Federer has been surprised by the standard of his performances. Admittedly, the 17-time major champion showed similarly scintillating form at Wimbledon in July, beating Andy Murray in straight sets, before losing convincingly to Novak Djokovic in the final.

He was also resoundingly beaten by Wawrinka in the French Open quarter-finals in June, when his compatriot went on to outclass Djokovic in the final and win his second major title.

Swiss rivalry
It marked a significant moment in the all-Swiss rivalry, largely because for a long time it was hardly a rivalry at all, with Federer stringing together 11 wins in a row against Wawrinka between 2009 and 2013.

“I think now we are both nervous when we enter the court. Before it was only me,” Wawrinka said.

“I was nervous because I knew I wasn’t at his level and now I think we can see that he is also nervous every time we play each other in the past few years.

“That’s a big difference because that shows how much he knows that I can play at his level, how much he knows I can try to play my game and not just try to react about what he’s doing.”