Greg Rusedski feels Marin Cilic has not been the same player since he beat Roger Federer in the 2014 US Open semi-final.
Cilic is hoping to cause another upset in New York tonight when he takes on Rafael Nadal in the fourth round.
But the Croatian has struggled for form since winning his maiden Grand Slam title five years ago.
“He is a worse player than when he won the title in 2014,” Amazon pundit Rusedski said of Cilic.
“It was actually Roger Federer that got nervous that year and Cilic grasped it and went after it.
“It is not forehands, backhands or serve, it is the mentality. He is putting too much pressure on himself.
“I almost want to take him out in the evening and have a few drinks and say ‘You relax, you have basically accomplished so much in this generation’.
“To win a Slam with the big three or big four is an incredible accomplishment.
Rafael Nadal has been told of a Marin Cilic issue (Image: GETTY)
Marin Cilic beat Roger Federer in the 2014 US Open semi-finals (Image: GETTY)
“I hope he can get that freedom back in his game and if he can he can have a big shot.
“But that is a big if because in his last match he served 17 doubles faults.
“If he does that then he will get punished against Rafa.
“I like that he is back in the mix. Even if he doesn’t win today but puts in a good performance that is a good sign for the future.
Marin Cilic takes on Rafael Nadal tonight (Image: GETTY)
“Marin is one of the more intelligent guys and you can’t start to think about things too much out there.
“But he might be a little bit more relaxed because he is in the second week.”
Nadal and Cilic clash in the opening match of the night session.
They are expected to get underway at midnight.