Every Grand Slam is going to have at least one major early upset and this week at the Australian Open, the victim was Novak Djokovic. The world No. 2 fell to Uzbekistan's Denis Istomin, 7-6 (10-8), 5-7, 2-6, 7-6 (7-5), 6-4.

This is the first time since Wimbledon in 2008 that Djokovic has been knocked out in the second round of a Grand Slam. So who exactly is Istomin and how did he get here?

The 30-year-old was born in Russia and lives in Moscow but represents Uzbekistan, and is coached by his mother, Klaudiya.

"When your family part of your team, it's great. I was lucky that my mother is coaching me. The also good thing that I don't need to pay the coach extra..." Istomin said. "We have good relationship. We understand each other very well."

He's currently ranked No. 117, a far cry from his career-high ranking of No. 33 back in 2012.  He finished four of the past six seasons inside the Top 100 and 2016 is the first time since 2009 that he hasn't ended inside the Top 100. Understandably, Istomin has been forced to spend a lot of time on the ATP Challenger tour lately, even starting 2017 with a second-round loss in Bangkok.

As part of a deal with Asia, the Slam awards one wildcard to an Asian player, but it wasn't just luck of selection. Istomin earned the main draw wildcard by winning the 16-player AO Asian-Pacific Wildcard Playoff in Zuhai. With the win against Djokovic, he now has six matches under his belt on his Australian Open journey.

While most tennis fans may not have heard of him, the Oakley glasses wearing Istomin is well known in both Russia and Uzbekistan. He was watched by the entire Tennis Federation of Republic of Uzbekistan, according to Gavhar Azimova, a member of the federation.

"We are ecstatic," Azimova told BBC Uzbek, "They [Denis and his mother] trained very hard. The whole Federation watched it live together. You say 'Istomin' and everyone knows him. The phones have not stopped ringing—we have had a barrage of phone calls saying congratulations."

Speaking of glasses, Istomin explained why he wears neon yellow specs (he likes to match the frame color with his bandana for fashion purposes).

"I was try the lenses, but I cannot play with lenses because it's bother me," he said. "I have a problem with one eye only, so I don't need for the second one. With glasses I feel more comfortable."

While this match is the biggest win of his career, Istomin has a lot more work to do to match the best wildcard performance in a major. That honor belongs to Goran Ivanisevic, who received a wildcard into the 2001 Wimbledon championships and went on to defeat Pat Rafter in the final.

Still, it's a great start for Istomin, especially compared to last year where he lost his first seven matches of the season.

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"It is the biggest win for me and it means so much, now I feel I can play with these guys and be with them on the same level," Istomin said.

Only time will tell whether Istomin can keep up this elite level of play or if he is a flash in the pan like so many other huge Slam upsets tend to be.

He will face Pablo Carreno Busta in the third round.

Follow Niko on Twitter: @nikovercelletto