With the 2013 US Open around the corner, former tennis pro John McEnroe doesn't foresee Roger Federer as a legitimate contender for the title. McEnroe believes age is catching up to Federer and the window for the 32-year-old Swiss to win another Grand Slam has closed, Reuters reports.

"To me, it's obviously going to be a lot more difficult at this stage," McEnroe said during a conference call, via Reuters. "I don't see at this stage him being able to go through all seven (rounds) and have to beat at least two of these (top) three guys.

"... When you've won 17 (Grand Slams), you clearly think you can win another one. To me, there comes a point, even as great as Roger has been for so many years, that it catches up to you a little bit.

"There are certainly scenarios where he could easily still get late into an event and even to a final. Andre (Agassi) got to the final of the Open at 35, so there's no reason to believe he couldn't do it. At Wimbledon I could see him going late into an event, a final. I could see it on a hard court...but I personally think that at this stage it's going to be quite, quite difficult for him to win another one."

McEnroe's opinion isn't unfounded. Federer's last Slam win was at the 2012 Wimbledon - World No. 116 Sergiy Stakhovsky bounced him at this year's Wimbledon in the second round. Federer is 32-11 on the season with one title. He started off well, but down the stretch of the season, suffered opening round losses in four of his previous six tournaments.

Federer, ranked No. 7 in the World, begins the hunt on Monday for his sixth US Open title.