Nadal's biggest flaw
Nadal's typical style of wanting to break players down with heavy topspin generally works well for him but by constantly looking for uncommon tactics, Nadal is overlooking the simple ones. When the opponent is tired, you want to make them run from side to side, bring them to the net and push them back again with lobs and make sure that even if they win the point they use a lot of energy doing it.
With guys like Soderling when he lost at the RG, and Djokovic today and previously, who can handle the topspin better than most, when things got tight Rafa just kept hitting the ball to them while they made him scamper all over the place.
He can place the ball well off both wings so it really shouldn't be too difficult for him to make his opponent move a little more. It's among the simpler tactics in the game and should be an obvious one. At 4-2 up in the last set with Djokovic (apparently) struggling to walk properly, hitting the ball back to him wasn't the smartest thing to do.
Red Grass Specialist