Novak Djokovic and Rafael Nadal share an incredible 43 Grand Slam titles between them - but old rival Andy Roddick is in doubt over who is more likely to add to their tally.
Djokovic ended a tumultuous year with a sixth ATP Finals victory and could dominate the sport next year as he aims to eclipse Nadal's collection of 22 Grand Slam crowns.
The Serbian legend's 21st Grand Slam win came at Wimbledon in July, but he was unable to take part at the Australian Open or US Open due to his covid-19 vaccination status. Meanwhile, Nadal won his 14th French Open before multiple injury setbacks derailed the end of his season.
