Novak Djokovic is opening up about his relationship with fellow tennis stars Roger Federer and Rafael Nadal, admitting that it's often strained.

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.

All of the attention will be on Andy Murray and Novak Djokovic's new partnership in the next fortnight at the Australian Open as the Scot named his all-time greatest tennis player