Of all the top guys, I think Federer and Djokovic hate losing the most....especially to each other Djokovic lost to Federer for 3 consecutive years at the U.S. Open (2007-2009) and was staring down the barrel of yet another loss when he found himself down match point. I think one factor that made him go for broke back in 2010 was that he was just sick of losing. He's talented and he knows it so he hit the ball harder, closer to the lines, and ended the rally with piercing swinging volley. He then fended off a 2nd match point just as offensively as he did the previous one. As for last year, I think he was just angry at the crowd decided to vent by whacking the return ("Take that, U.S. Open crowd!...oh s**t, it went in!") Same with Federer: after that U.S. Open loss in 2011, Fed went on an absolute tear and didn't lose another match until the Australian Open SF. I think losing is a great motivator for a lot of people, especially for guys like Djokovic and Federer. And perhaps losing a close U.S. Open final could be the catalyst for another stellar year.