Djokovic won the latest installment of his thrilling rivalry with Andy Murray as the world number one fought back to secure a dramatic 4-6, 6-3, 7-5 victory in the ATP Tour Finals at London's O2 Arena on Wednesday.
Djokovic has a 100 per cent record after two Group A matches at the season-ending event and will be guaranteed a place in the semi-finals if France's Jo-Wilfried Tsonga defeats Czech fifth seed Tomas Berdych later yesterday.
World number three Murray now needs to win his final group match against Tsonga on Friday to avoid an early exit after the US Open champion failed to take advantage of a promising start.
Djokovic and Murray have been on-court rivals and off-court friends since the day they first faced off at an Under-12s tournament in the south of France.
And, with Roger Federer approaching the end of his career and Rafael Nadal hampered by knee problems, their meetings have emerged as the sport's most significant occasions.
In 2012 alone they have clashed seven times, with Djokovic starting the year with victory in the Australian Open semi-finals and Murray getting his revenge with an Olympic last four win and then, even more significantly, a five-set triumph over the Serb to win his first Grand Slam title at the US Open. Djokovic won their most recent meeting in the Shanghai final after saving five match points and his self-preservation instincts helped him survive another epic showdown lasting two hours and 34 minutes.