Murray loses to Tipsarevic in Abu Dhabi

Ahead of his title defense in Abu Dhabi, Djokovic said he was excited about the 2013 season and that he's making the French Open -- the only Grand Slam tournament he has yet to win -- his top goal of the year.

"I managed to have the best year of my career in 2011 and I knew that it was going to be difficult in 2012 to maintain No. 1 in the world and play consistently," Djokovic said.

"I did, and so this year was an even more successful year from a psychological aspect. ... Ambitions are always high and I want to win every Grand Slam and major tournament I play and this year is no different."