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.

CNN: Grieving Djokovic faces Nadal in final

In the history of women's tennis, only Steffi Graf has won the Golden Slam, 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.

WSJ: Social Media

Victory gave the 19-year-old what came to be known as a "golden Grand Slam", adding the Olympics to the four major titles she won that year.

BBC: SPORT | Olympics 2004 | Tennis | History | Tennis serves up shocks