Robin Soderling
If by '2008 men's single' you mean Wimbledon, then Rafael Nadal. Nadal also beat Federer in the French Open.
There are countless professional tennis tournaments each year. There is no one extremely important tournament. The four grand slams (US Open, French Open, Wimbledon, and the Australian Open) are the biggest tournaments in tennis each year. in 2012 Novak Djokovic won the Australian Open and the three others have not been played yet.
Rafael Nadal (retired)
Rafael Nadal beat Roger Federer in the longest Wimbledon final match ever to win the men's single title in 2008. He had lost t he previous 2 finals to Federer, but finally came thru in 2008.
Tennis US Open champions 2010:Men's singles - Rafael NadalWomen's singles - Kim ClijstersMen's doubles - Bob Bryan and Mike BryanWomen's doubles - Vania King and Yaroslava ShvedovaMixed doubles - Liezel Huber and Bob Bryan
Sadly Rafael Nadal. But Lately Federer beat him the last 2 times they played.
Rafael Nadal beat Tomas Berdych in the final of Wimbledon 2010.
6-4 5-7 6-4 6-2
The Spanish tennis player Rafael Nadal beat Roger Federer in 4 sets (6-3, 4-6, 6-3, 6-4) in a little over three hoursto win the men's singles title for the 3rd consecutive year at the 2007 French Open.
Andre Agassi
Roger Federer beat Andy murray by 3 sets to 1.