The Serbian beat Nadal 4 - 6 6 - 3 6 - 2 in two hours and 25 minutes .
The Serbian guaranteed the number two ranking by defeating Roger Federer in the semis .
The Serbian , who guaranteed the number two ranking by defeating Roger Federer in the semis , beat Nadal 4 - 6 6 - 3 6 - 2 in two hours and 25 minutes .