Korea's Chung beats Djokovic 6-7 (4-7) 5-7 6-7 (3-7)
Djokovic struggling with elbow injury in fourth-round match
World number 97 Tennys Sandgren beats fifth seed Dominic Thiem
Halep beats Osaka to reach last eight
Federer wins in straight sets
Kerber and Keys also through
Djokovic 6-7 (4-7) 5-7 3-3 Chung*
Pick that out. Leaning back, opening up the body, finding the line with a forehand winner. Neat from Hyeon Chung.
He gets a backhand slice all wrong on the approach though, and Djokovic garners break point.
David Law
Radio 5 live sports extra commentator at Melbourne Park
It'll be interesting to see if Chung can close it out against one of the all-time greats.
Djokovic 6-7 (4-7) 5-7 3-3 Chung*
Hyeon Chung overcooks a crosscourt forehand, he was eyeing up the postage stamp spot, but has stuck it on the tramlines. That's never getting delivered.
The 21-year-old cannot fend off another Djokovic attack, and slips to 15-30.
Djokovic 6-7 (4-7) 5-7 3-3 Chung*
A solid hold for Novak Djokovic.
We're at 3-3 in the third set.
Image source, Getty Images*Djokovic 6-7 (4-7) 5-7 2-3 Chung
Hyeon Chung clips the net with a forehand and that could go anywhere, but it loops long.
Novak Djokovic follows up with his first ace of this last-16 match - one apiece.
The Serb cruises to 40-0, before Chung scrambles into a forehand winner from close range.
Image source, Getty Images
Mark Woodforde
Australian 12-time Grand Slam doubles champion on BBC Radio 5 live sports extra
I think Djokovic is surprised at Chung's ability tonight. You can see him running after the ball, thinking 'You're kidding me'.
*Djokovic 6-7 (4-7) 5-7 2-3 Chung
Hyeon Chung sends a relatively straightforward forehand long and that's the break.
Does anyone want to hold in this match?! We've seen more breaks than the Crucible...
Djokovic 6-7 (4-7) 5-7 1-3 Chung*
Sublime! I'm running out of superlatives...
Novak Djokovic looked beaten, only to eek out a winning volley like Stretch Armstrong down to his right.
This one's tense.
Break point.
Djokovic 6-7 (4-7) 5-7 1-3 Chung*
How about that!
Chung jabs Djokovic into the corner before unleashing a knockout forehand winner.
Deuce.
Djokovic 6-7 (4-7) 5-7 1-3 Chung*
Aggressive from Chung, forcing Djokovic deep, only to watch the Serb flip the point on its head and make the Korean defend.
But he does, superbly. Chung claws one break point back.
One more to go.
David Law
Radio 5 live sports extra commentator at Melbourne Park
This is vintage Djokovic now, the way he's returning the ball.
Djokovic 6-7 (4-7) 5-7 1-3 Chung*
Now he gets the break point chance, as Chung flicks a forehand from deep into the roots of the net.
Big chance.
Djokovic 6-7 (4-7) 5-7 1-3 Chung*
Every now and then Novak Djokovic shows a glimpse of the brilliance that has won him six Australian Opens - that was one of those glimpses, picking off Hyeon Chung with effortless precision.
The 30-year-old scrambles to 0-30. A huge top spin forehand follows, but Chung has the measure of it and his response is too hot for Djokovic to handle.
Djokovic 6-7 (4-7) 5-7 1-3 Chung*
Long again from Novak Djokovic, leaning back and whacking a forehand as if he were stepping up to the plate in the MLB.
Break point Chung.
Wide from Djokovic. Chung breaks.
*Djokovic 6-7 (4-7) 5-7 1-2 Chung
Probably given Hyeon Chung the live text commentator's curse there, if such a thing exists...
He wraps a forehand into the net. Novak Djokovic can't punish the Korean though, serving his ninth double fault of the match.
The Serb goes wide from mid-court, and that's deuce.
*Djokovic 6-7 (4-7) 5-7 1-2 Chung
Novak Djokovic hasn't been at his best today, but Hyeon Chung has impressed against the six-time champion.
The 21-year-old's powerful return forces his opponent to go long, but Chung can't back that up and he trickles a backhand into the tramlines.
Another follows - 30-15.
David Law
Radio 5 live sports extra commentator at Melbourne Park
Maybe I'm reading too much into it but I think Djokovic is using this match as a yardstick. I don't think he expects to win.
*Djokovic 6-7 (4-7) 5-7 1-2 Chung
Lovely stuff. Novak Djokovic tempts Hyeon Chung to go right, but the Korean flicks a backhand left instead.
He then sizes up a short ball from the Serb and hammers it across court to hold.
Djokovic 6-7 (4-7) 5-7 1-1 Chung*
Image source, AFPThe Hyeon Chung support are enjoying what they've seen on Rod Laver Arena today.
Their man moves into a 30-15 lead as Djokovic flops a lethargic-looking forehand long.
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