It will remain an oddity in Stan Wawrinka’s life and career that, but for one person, he would have been remembered as the finest male tennis player Switzerland had.

They meet again, in the semi- finals of the US Open, and there is not a judge worth listening to who could confidently predict which Swiss will be in the final.

Both won impressively on Wednesday night, sneaking in before the rain came, Wawrinka probably more easily in dispatching Andy Murray's conqueror, Kevin Anderson, in three sets than Federer's win over Richard Gasquet.

Federer has yet to drop a set in this tournament.

The attention, as ever, will be focused on Federer, who might yet win his 18th major here. At 34 he is playing tennis every bit as good as that when he was at his glorious best. His golden career has no definable sunset.

“Since a few years now I have tried to look at the big picture to hopefully still be playing at a high level at this age,” he said.

“So in some ways I am not surprised I am playing as well as I am. I think I’m volleying better than I have the last 10 years because my serving is working quite well. You put those two things together, and standing in on the return as well, I think has changed the dynamics.”

Regarding Wawrinka he said: “It took him a while to figure out exactly what his possibilities were. I don’t think he was a guy who always had enough confidence.”

Break through Then Federer became seriously laudatory about a guy his wife, Mirka, had ridiculed so publicly at the World Tour Finals last year. "I always thought he was a better player than he actually was but somehow something was holding him back, maybe. Once he really started to break through and he had some big wins [he changed].

“Then in practice he started working to hit the ball harder. Today he can consistently bring the power on forehand, backhand and serve almost [as well as] anybody when he gets hot. I’m happy he found that level of play here.

"Two slams, Davis Cup, Olympic gold. He has a complete career. He won a Masters 1000. He has everything he ever wanted. He has had a wonderful career.

“I’m looking forward to playing him. He definitely is a big challenge for me. He beat me in straight sets at the French, so I hope I can do better this time.”

Wawrinka’s win over Anderson on the Louis Armstrong court where the South African had beaten Murray two nights earlier in four sets, was hugely impressive, full of robust hitting and precision. If he plays that way against Federer, he will be difficult to contain.

Best match "For sure, it was the best match of the tournament for me," Wawrinka said later.

It has been a slow burn for a player who sometimes struggles to find his best tennis, as he pointed out: “You could see how I was playing at the beginning of the tournament. I wasn’t playing the best but I was trying to get through the first week. “

Now his mood – after the distraction of the Nick Kyrgios sledge in Montreal and the fallout that followed – has switched entirely, from diffidence to total confidence, not only about beating Federer but winning a third major.

“I just know that I can do it, for sure. I did it twice.”

The second of Wawrinka's majors, beating Novak Djokovic at Roland Garros, was probably the match of this year, stopping the world number one in his charge for a calendar grand slam with power tennis that was irresistible. Wawrinka hit the ball that day as hard as anyone has all season.

He beat Federer on his way to that final and his three wins over him have all been on clay, so the challenge now is a different one, at a place where Federer won five titles in a row.

Wawrinka, however, is moving closer to him on hard courts, in more ways than one: at one point in his 6-4, 6-4, 6-0 win over Anderson, he played the shot Federer has introduced to his game in recent weeks, the charge into the service box on returning a second serve.

So the quiet man who watches and learns is in a good place again. He may well surprise his friend one more time. Guardian Service