Denis Istomin is coached by his mother and wears glasses for eyesight problems. But after his sensational dethroning of Australian Open champion Novak Djokovic, the unlikely hero could finally become a star, at least in his homeland of Uzbekistan.

The 117th-ranked Istomin caused one of the biggest Grand Slam upsets when he knocked out the six-time winner in the second round, 7-6 (10/8), 5-7, 2-6, 7-6 (7/5), 6-4 in 4hr 48min.

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.

Istomin, distinctive by his brightly coloured glasses, can expect to become an instant sensation after conquering the 12-time Grand Slam winner on his favourite court.

"It means so much for me to beat world number two," said the 30-year-old journeyman, who only got into the tournament main draw as the winner of the Asia wildcard play-off.

"I just hope that it is not only one victory of mine. I'm trying to keep going the same way and trying to win some more."

Istomin spent three months in hospital and was out of tennis for two years after breaking his leg so badly in a 2001 car accident that doctors doubted he would ever play competitive tennis again.

But with the coaching of his mother Klaudiya Istomina, he has been back on the circuit since 2004 -- although beating Djokovic is his career highlight by some distance.

Asked what he would say if someone had told him he was going to beat Djokovic, he replied: "I would say, 'Are you crazy or what?' Especially in five sets, for sure.

"For me, it was impossible to think about that I can hold it five sets with Novak, physically and mentally. So I did well today."

Istomin, who will play Spanish 30th seed Pablo Carreno Busta in the third round, joked that he saves money by having his mother as his travelling coach.

"When your family is part of your team, it's great. I was lucky that my mother is coaching me," he said.

"The other good thing is that I don't need to pay the coach extra, you know."

And what did his mother say to him after the match? "She said, 'Good job'," he smiled.

Istomin said he has never been the most famous athlete in Ukbekistan, although now that might change.

"Maybe now I will be. But I'm not a superstar in Uzbekistan. I've been living in Moscow for 10 years so I don't go too much to Uzbekistan," he said.

"But of course, if I play in Uzbekistan, everybody knows me."