Rafael Nadal up 5-4 in first set

Rafael Nadal is up a break, leading 4-3 in the first set.

Novak Djokovic needs to be careful. He lost his composure earlier in this set. Plus, Nadal is unbeatable when winning the first set in Grand Slam matches (107-1).

It could be a historic day for Nadal as he looks to complete the career Grand Slam.

UPDATE (5:05): Nadal holds and is up 5-3. They're talking about it on the CBS telecast: is Djokovic's left ankle, which he hurt against Roger Federer, bothering him today?

UPDATE (5:07): Djokovic battles back, trails 5-4. Nadal will be serving for the set. This is a big game for Djokovic. He can't fall behind against Nadal.