French Open champion Stan Wawrinka on Wednesday hailed Roland Garros semi-final opponent Andy Murray as being in a different class despite both men having captured two Grand Slam titles each.

The pair meet Friday for a place in the final when the 31-year-old Swiss will try to back-up the title he won 12 months ago in a sensational win over Novak Djokovic while Murray bids to be the first British man in the Paris final since Bunny Austin in 1937.

But Wawrinka insists their two careers have been on different trajectories.

“I think he is well ahead of me. Now that I’ve won a second Grand Slam people say I’m closer to him because I have won two and he’s won two as well,” said Wawrinka, who was also Australian Open champion in 2014.

“But if you were to compare our two careers he’s well ahead of me given all the titles, the finals, number two in the world, and he has so many Masters 1000, as well.

“Therefore, as I keep on repeating, he’s in the ‘Big Four’ (with Djokovic, Roger Federer and Rafael Nadal). There is a reason for this. Maybe he has fewer titles than the other three, but he’s always been with them during the semis, the finals. His career is very, very impressive.”

Wawrinka has a career haul of 14 titles, including his two majors and one Masters.

Murray, the 2012 US Open and 2013 Wimbledon champion, has racked up 36 titles with 12 at the Masters level.