Roger Federer is the best tennis player in the world today. However, there are four players who can give him fits should he end up playing them. They match up well and have been able to beat him at the highest levels of various tournaments.
Federer should still be one of the primary competitors in this year's U.S. Open, but don't be shocked if he runs into one of these four and winds up in trouble.
Despite being one of the worst in terms of head to head record versus Roger Federer, Andy Roddick always seems to give him headaches. Since 2006, the two stars have faced off 13 times with Federer winning 11 of them.
However, that doesn't exactly paint the right picture because in 10 of the 13 matches, they have split the first two sets and had to draw their matches out even longer to three and sometimes even four sets. Roddick may not be the same player he was when he was the No. 1 player in the world, but he can still compete with Federer as shown in his victory earlier this year.
Despite not beating the Swiss star since 2009, Juan Martin Del Potro has proven that he is more than able to take Roger Federer to his absolute limit. Federer may hold a 13 to two edge over the 23-year-old, but they have played every set extremely competitively over the past year.
Over the last seven matches, Federer has lost multiple sets to the young 6'6" Argentinian despite having the seven match winning streak. Federer seems to have trouble hitting it out of Del Potro's ridiculously massive reach that is surely acquired from his long, basketball player style frame.
Novak Djokovic is the best tennis player not named Roger Federer in the game today. He's also one of the few men who have come close to even tying Federer in a head-to-head series. They currently are 16-to-12 in the series standings.
Federer is leading in those, but at the same time, a four match difference is not a huge lead considering that over the past two years, Djokovic has won six of the last nine matches. They play every match ridiculously close and in six of those nine matches, have taken the games to three sets or more.
Gold medal winning Andy Murray is the thorn in Federer's side. The overall series stands at nine-to-eight, but what's more telling is that Murray and Federer always have extremely competitive and close matches just like what two of the top four players in the game today should have.
Despite Federer winning three of the last four versus the British star, Murray still holds the edge in the series. This is due to Murray winning six of their first eight matches against each other and holding the lead in the series ever since.
Their styles match up well, but if there is one man who would be worth putting money on in a match against Federer, it's Andy Murray.
All match stats are from the ATP official website.
Scott Carasik is a Featured Columnist and Trends and Traffic Writer for Bleacher Report. As a Featured Columnist, he covers the Atlanta Falcons, NFL and NFL Draft. He is also the Falcons analyst at Drafttek, runs the NFL Draft Website ScarDraft.com and hosts Kvetching Draftniks Radio.