MELBOURNE, Australia — And then there was one: The Big Three is down to just Novak Djokovic , who stands alone from a golden generation of men’s tennis now that Rafael Nadal has joined Roger Federer in retirement .

Jim Courier won 23 career titles and earned over $14 million in prize money, but a lack of motivation led to his early retirement.

"I accepted it as it is. I understood the messaging that I got, which was we are rivals and nothing else,” Djokovic said