Winning three more Grand Slams would take him past Bjorn Borg, Rod Laver and Roy Emerson on the all-time list, and in sight of Pete Sampras and Rafael Nadal, who both have 14 to their name.
Roger Federer's record of 17 remains the ultimate goal. Djokovic has nearly six years on Federer, but modern history suggests such relentless success will be extremely difficult to sustain into his 30s.
Watching him now, though, makes anything seem possible. Djokovic reached all four of 2015's Grand Slam finals, losing only to Stan Wawrinka in the championship match at the French Open.
He is already guaranteed to end the year as the world number one for the fourth time in five seasons: only Federer, Sampras and Jimmy Connors have done so more frequently.
17: Roger Federer
14: Pete Sampras, Rafael Nadal
12: Roy Emerson
11: Rod Laver, Bjorn Borg
10: Bill Tilden, Novak Djokovic
