Djokovic beat Nadal in January's six-hour Australian Open final to claim his fifth major title and set up the prospect of a "golden slam" -- unprecedented by a male player -- this year.
In the history of women's tennis, only Steffi Graf has won the GoldenSlam, and in her case it was the even more elusive Golden Grand Slam a gold medal in the same calendar year that she also won the Grand Slam, a rare achievement that can only happen if a player is peaking during an Olympic year.