THE last time Andy Murray met Stanislas Wawrinka in New York, the Swiss wiped the floor with him in just the third round.

The defeat characterized the bad old Murray of yesteryear; back then you just never knew what to expect from the world No.3.

Coming off the back of another dose of Wimbledon heartache, it was tough to take. Murray, not for the first time, was muddled, out of sorts and failing to deliver. It still sends a shudder down his spine.

Fast forward three years, though and the plates have shifted - for both players. The 26 year-old meets the entertaining and in-form Swiss here as a defending US Open champion with a glorious Wimbledon triumph also in his locker. He's a different animal. So to is Wawrinka.

Forever a talent, yet forever in Roger Federer's shadow, the world No.10 has enjoyed the finest 12 months of his career, memorably coming within a whisker of shocking Novak Djokovic at the Australian Open before winning a title in Portugal and reaching the final of the Madrid Masters where he came unstuck against the king of clay, Rafael Nadal.

A superb win over Tomas Berdych though has set up the chance to reach his first US Open semi-final.

Murray may have dropped another set against Denis Istomin (6-7 [5-7] 6-1 6-4 6-4), on Wednesday night in a match which came just hours after Djokovic had destroyed the hapless Marcel Granollers, but the tricky wind and even trickier opponent ensured all that mattered was getting the job done for the Scot.

Wawrinka was easily dispatched in the Olympics last summer yet, when they meet here today, memories of that 2010 defeat are bound to creep into Murray's mind.

"When I played him here last time it wasn't a happy tournament for me," admitted Murray. "I struggled. I didn't play particularly well that day, and I've struggled on that court. I don't have particularly good memories from that match, really. I did go away from it a little bit down. That was a tough loss, for sure.

"But I also played him on [Arthur] Ashe a few years ago, and played a really good match, so I've had quite mixed results against him. It should be a really interesting match."

Djokovic, who faces Mikhail Youzhny in today's other quarter-final, has reached this stage without moving out of second gear while Nadal, who played Tommy Robredo overnight, has also looked ominous.

Such is Murray's confidence right now, neither worry him. "I always say that in tennis, and any individual sport, it doesn't really matter what happened two days ago," added the Scot. "You turn up on the day of the next match and you might feel awful. You never know. It doesn't matter how you've played up to this point; you can always get better - or get worse. It looked like he played extremely well against Granollers. But the matches will get tougher now."

Wawrinka will certainly ensure that rings true. The way he took Djokovic apart in Melbourne in January helped him believe he belongs in the upper echelons of the game. His energetic, all action game mirrors that of Murray and should ensure a typically rollercoaster affair.

"That was the match that meant so much for my confidence," said the Swiss. "I am quite an unsure guy on the court, I always have some doubts and, after that match, I had the feeling that everything I was doing outside, the practice, was in the right direction. I just needed to keep focusing on that because my level was there and I could play for five hours against the No.1 player and he was quite impressive all the tournament and for me it was a loss but a victory inside.

"Tennis is very much in the head, the top 20 players play amazing tennis but the changes are in here, mentally. Now I am not young. At 18, 20 you don't think too much and you enjoy, or try to and you don't see what a victory or a loss can give you but now it is different, I am much more mature. I hope I have much more to come.

"To beat Murray, I have done three quarters here and never been to a semi-final and to win this would be another huge change but the most important thing is to play and practice well.

"I needed one or two matches here to get the confidence back and that is what happened. I know that everything can happen now but also I am playing Murray and even if I play my best match I can still lose because he is the top of the tops."

The pair are good friends, practicing regularly with each other, therefore ensuring there are no secrets in their games. When they met in Monte Carlo earlier this year, Wawrinka won on the red dirt, which has never been particularly kind to Murray. The New York concrete suits the Scot better, though.

But Wawrinka is ready. "I am sure he will not be 100% confident as he knows how well I can play," he said.

Murray has been warned.