Nadal leads Del Potro 7-3 in their career head-to-head, but this is not surprising since Nadal has a favorable record against every player in the Top 10. In fact, it would be a good question to find out if there is anyone who has a career head-to-head advantage over Nadal who has played him at least twice. Anyway, Del Potro has also delivered the worst beating the Spaniard has ever faced on a hard court with a memorable 6-2 6-2 6-2 drubbing in the 2009 US Open semifinals on his way to winning the title, becoming the first man to beat Nadal and Roger Federer en route to winning a major title. That was also the last time Nadal lost to the 6'6" Argentine, but the two have only played twice since, with no meetings at all in 2010 or 2012.
This final is very important to both players, so it should be an extremely hard-fought match. Nadal is trying to win his 600th career match, to join his arch-rival/frenemy Federer as the only other active player with that many wins. (Federer is closing in on 900 wins, with 888 right now.) He is also trying to win his record 22nd ATP Masters Series shield, breaking a record he currently holds with Federer. But Nadal has 3 clay court Masters series tournaments (in, Monte Carlo which he has won 8 times already, in Madrid and in Rome). Nadal has lost the last 6 hard-court finals he has played in, but then again he was facing Djokovic in those finals. If Djokovic had somehow won his semifinal match with Del Potro, he would be the favorite in today's final.
Del Potro on the other hand is trying to win his first Masters series title and make a claim for his place at the top of men's tennis. There's no question Del Potro has the ability to beat Nadal, but can he do it one day after playing a nearly 3-hour match against Djokovic? That is the question that will be answered later today, and the answer could have a large impact on what happens in men's tennis for the rest of the year. Del Potro must be considered the under dog, but I think he will pull off the upset.
Prediction: Del Potro.