Korea's Chung beats Djokovic 6-7 (4-7) 5-7 6-7 (3-7)
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*Djokovic 6-7 (4-7) 5-7 5-6 Chung
I said Hyeon Chung doesn't like to celebrate, but that passing forehand as he was scuttling back towards his own baseline brings a huge roar and fist pump to boot.
The 21-year-old pulls out a massive hold.
He's one game away from the quarter-finals.
Djokovic 6-7 (4-7) 5-7 5-5 Chung*
The Korean picks a passing backhand winner out of his arsenal, that's one for the highlights reel.
He follows up with a nonchalant forehand winner, just opening up and whipping it down the line with more spin an election campaign.
Novak Djokovic clips the net from the next point, and all of a sudden it's 40-30.
Image source, Getty Images#bbctennis
Stephanie Siu: Listening to Djokovic getting beaten by Chung Hyeon at work. It's rather unsettling but exciting all at the same time.
Djokovic 6-7 (4-7) 5-7 5-5 Chung*
Hyeon Chung pops a forehand long from his own baseline, he was scraping around his feet to pick that one up.
Double fault.
A chance for Djokovic...
Mark Woodforde
Australian 12-time Grand Slam doubles champion on BBC Radio 5 live sports extra
At some stage, you would expect some sort of fatigue from Chung's end of the court. That's why it's imperative he wins in three sets.
Djokovic 6-7 (4-7) 5-7 5-5 Chung*
Hyeon Chung seemed to have all the time in the world there to pick out a dipping backhand winner across court, it almost just toyed with Novak Djokovic.
The Serb responds with another punchy serve that reverberates through the Korean's racquet, and Djokovic holds.
*Djokovic 6-7 (4-7) 5-7 4-5 Chung
The Serb shrugs his shoulders as he reaches for his towel - how do you answer Hyeon Chung in this sort of form?
A thumping second serve will do it, forcing the Korean's return into the net and his next one to drift well wide.
Image source, Getty Images*Djokovic 6-7 (4-7) 5-7 4-5 Chung
Novak Djokovic will have to serve to stay in the Australian Open.
*Djokovic 6-7 (4-7) 5-7 4-5 Chung
Wonderful from Hyeon Chung, squatting to meet a stroke with both hands gripping his racquet and placing it beyond a despairing Novak Djokovic.
The Serb slips a forehand into the tramlines.
Chung holds.
Mark Woodforde
Australian 12-time Grand Slam doubles champion on BBC Radio 5 live sports extra
Wow!
Djokovic 6-7 (4-7) 5-7 4-4 Chung*
Hyeon Chung doesn't really do celebrations, so a little nod of appreciation is enough to sum up a fantastic winner after an epic rally that had both players scrambling at one point or another.
Super from the Korean.
That's deuce.
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Djokovic 6-7 (4-7) 5-7 4-4 Chung*
It's fits and spurts for Novak Djokovic at the moment - he slips right off the pace and then accelerates to top gear, it's like teaching my younger brother to drive all over again...
The Rod Laver Arena crowd must be feeling motion sick.
Hyeon Chung clips a drop shot in, Djokovic responds by sprinting forward and placing a winner to the Korean's left.
He flaps his arms to gee up the crowd. They're loving it - 15-30.
Djokovic 6-7 (4-7) 5-7 4-4 Chung*
Novak Djokovic scrambles to deuce, and Hyeon Chung goes long off the next serve.
Beautiful, drifting forehand from Djokovic to send Chung wide and the Korean can't muster a response.
The six-time champion holds.
Mark Woodforde
Australian 12-time Grand Slam doubles champion on BBC Radio 5 live sports extra
Djokovic is struggling when he doesn't get the ball out of the middle of the racquet - the reverberations are shooting up his arm.
*Djokovic 6-7 (4-7) 5-7 3-4 Chung
How did Hyeon Chung get to that? He looked beaten by a cracking Novak Djokovic stroke, only to straight bat a forehand down the line and watch it crack the Serb's racquet around his ankles.
He earns break point with an equally ferocious backhand.
*Djokovic 6-7 (4-7) 5-7 3-4 Chung
Djokovic pops a forehand wide, rolls his shoulder back and looks at the elbow that's been causing him problems.
A quick shake out and he nails a first serve winner, before bouncing on to a short Hyeon Chung return to hammer a huge forehand home.
Mark Woodforde
Australian 12-time Grand Slam doubles champion on BBC Radio 5 live sports extra
I've been impressed with Chung's intensity. He's out-Djokovic'd Djokovic.
*Djokovic 6-7 (4-7) 5-7 3-4 Chung
Chung holds. A big, big hold too. Djokovic looked to have the momentum.
Djokovic 6-7 (4-7) 5-7 3-3 Chung*
Good hustle from Chung, who has Djokovic almost crying out trying to stay in the point, only to then drop a loose slice into mid-court.
Djokovic slices back, coaxes Chung in and then puts a volley wide - no one wants to win it!
Chung moves to advantage.