Before his final round-robin match against Andy Roddick, the world No. 3 emerged from the locker room wearing a novelty eyepatch. It was a cheeky nod to Djokovic's previous match against Rafael Nadal, in which the Serb struggled with his eyes and frustrated Nadal with long delays to tend to the problem.
Djokovic said something lodged into his eye during the first set against Nadal and that he was unable to see for much of the match because of the "irritation."
After the match he said (via Reuters):
"Playing with one eye, especially against Nadal, is not enough. [...] I feel sick even talking about it to be honest. It's just incredible that this happened to me because it never happened in my life. I was feeling great."
He went on to lose that match, but still had the good sense of humor to reference his ocular troubles before playing Roddick. Djokovic wore the joke-store eyepatch during his entrance and handed it to a small child before warming up.
They don't call him The Joker for nothing.