Novak Djokovic paid tribute to his long-time rival Roger Federer on Friday, hailing the "incredible moments and battles" the pair shared on court.

Rafael Nadal says the emergence of a new generation is just what tennis needs, while welcoming back old foe Roger Federer to help him keep them at bay.

Novak Djokovic and Roger Federer are poised to become the first $100 million men in tennis in 2016, in a gripping sub-plot to the new Grand Slam season.