Federer and Wawrinka will play their second match of the day later tonight after both booking their place in the quarter-finals.
Three-time Grand Slam winner Wawrinka is the massive underdog after only recently returning from a long-term injury.
The world No 151 beat Novak Djokovic to win the French Open final in 2015 and such experiences should help him in his quest to overthrow Federer tonight, says Rusedski.
“Of course Stan believes he can beat him,” Rusedski told Sky Sports.
“Wawrinka has won three major titles. There are very few players who have done that.
“The only one missing from his resume is the Wimbledon Championship. That in itself is impressive.
“I think Stan will be very pleased. The first time he has won three matches since coming back from the knee surgeries.
“To play Federer, all the pressure is on Roger. Everybody is expecting him to win.
“When Stan can roll out there he is dangerous.
“Don’t forget that French Open final when he played Djokovic and everybody says Djokovic is going to win.
“But Stan blitzed him and won in four sets to win the French Open title.
“So don’t underestimate Stan the Man.”
However, Rusedski was reluctant to give Wawrinka his backing to get the win.
“I am going to stick with Federer but would I be surprised if it goes tight that he has got a shot?” he added.
“He has got a shot. A legitimate shot.”