Defending champ Djokovic stunned by Istomin

Melbourne : Defending champion Novak Djokovic was sensationally knocked out in the second round of the Australian Open by unheralded Uzbek Denis Istomin in a major shock on Thursday.

The 117th-ranked Istomin ousted the six-time winner 7-6 (10/8), 5-7, 2-6, 7-6 (7/5), 6-4 in 4hr 48min on Rod Laver Arena.

It was the world number two's earliest Grand Slam exit since Wimbledon 2008, when he was beaten by Marat Safin in the second round.

It was also only Djokovic's second loss to a player outside the top 100 in seven years, after his defeat to 145th-ranked Juan Martin del Potro at last year's Rio Olympics.

"He played obviously above his level. You got to give him credit for that," Djokovic said. "Many things came together for him today. He's a well-deserved winner. 

"He deserved to win. No doubt, he was a better player in the clutch moments. There's not much I could do."

Istomin, who got into the main draw as the winner of the Asia wildcard play-off in December, said it was the high point of his playing career.

"It is the biggest win for me, and it means so much," Istomin said, struggling with the emotions of his achievement.

"So now I can feel that I can play with these guys and to be with them on the same level."

He added: "I feel sorry for Novak. I was playing so good today. I mean, I also surprised myself today."

Serbia's Djokovic was bidding to win a record seventh Australian Open title and overtake Australian Roy Emerson, who won six in the 1960s.

It was a miserable start to the Grand Slam season for Djokovic, who surrendered his top world ranking to Andy Murray last year and fell to second in the world for the first time since June 2014.

Istomin played at an extraordinary level from the opening game, which took 16 minutes -- signalling the impending struggle for Djokovic.