Denis Istomin pulled off one of the great all-time Grand Slam shocks as the wild card and world number 117 defeated six-time Australian Open champion Novak Djokovic in the second round in Melbourne.

In possibly the biggest upset of his career, the defending champion went down 6-7(8) 7-5 6-2 6-7(5) 4-6.World number two Djokovic lost the first set in a tie-break to the Uzbek, after an opening game which lasted a full 16 minutes.

He responded by taking the next two sets but again on a tie-break in the fourth, Istomin's big hitting proved the difference.

And Djokovic was eliminated in the second round of a Grand Slam for the first time since Wimbledon in 2008 courtesy of a solitary break in the fifth. It is the earliest he has been knocked out of the Australian Open since 2006, when he lost in the first round aged 19.

The Serb came into the fortnight looking to wrest back world number one status from Andy Murray but now faces seeing his big rival win in Melbourne for the first time, with Murray now the clear favourite for the tournament. 

The loss to Istomin is the second time in three Grand Slams that Djokovic has fallen victim to a huge shock after he lost to American Sam Querrey at Wimbledon last year.