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Now: Nick Kyrgios 5-7 6-4 3-6 7-6 (7-2) 6-4 Ugo Humbert
Simona Halep fights back to beat Ajla Tomljanovic 4-6 6-4 7-5
Novak Djokovic beats Frances Tiafoe 6-3 6-7 (3-7) 7-6 (7-2) 6-3 to reach third round
Serena Williams & Naomi Osaka through but Bianca Andreescu & Petra Kvitova knocked out
Dominic Thiem wins in straight sets, Stan Wawrinka loses in five
Day three from the Australian Open at Melbourne Park
*Kyrgios 5-7 6-4 3-6 7-6 (7-2) 0-1 Humbert
Humbert is unruffled and earns a break point with a wonderful winner down the line.
That sees Kyrgios explode again and have another row with umpire Marijana Veljovic.
She comes down off her seat to fiddle with the net as Kyrgios remonstrates.
Image source, Getty Images*Kyrgios 5-7 6-4 3-6 7-6 (7-2) 0-1 Humbert
Uh oh. It's Kyrgios versus the net let machine, again.
Kyrgios is FURIOUS! He swipes the net with his racquet after claiming his serve was about a foot over it.
He'd better be careful. He's already had a point docked, next time it is a game...
Image source, Reuters*Kyrgios 5-7 6-4 3-6 7-6 (7-2) 0-1 Humbert
The key for Kyrgios is keeping that balance between playing freely and being too casual.
The latter sees him trail 0-15 before the former helps level.
A big serve puts him 30-15 ahead, but then he wallops a forehand long and that's 30-30...
*Kyrgios 5-7 6-4 3-6 7-6 (7-2) 0-1 Humbert
I mean, this is exhibition stuff bordering on the ridiculous. Kyrgios tries a 'tweener as we get back up and running in the fifth.
That doesn't quite lead to the result he wants, helping Humbert into a 30-15 lead.
Make that 40-15. Then the game. A wild crosscourt backhand goes into the tramlines.
Anne Keothavong
Former British number one on Tennis Breakfast
I'm speechless. Humbert has gone off the court and I don't blame him. For that set to slip away... you have to feel for the Frenchman. The crowd were cheering when he dumped a first serve out or in the net. It felt like a Davis Cup atmosphere.
Image source, Reuters
Russell Fuller
BBC tennis correspondent on BBC Radio 5 Live Sports Extra
Nick Kyrgios has won seven of his nine five-set matches. Ugo Humbert has won one of three.
Kyrgios 5-7 6-4 3-6 7-6 (7-2) Humbert
Which way is this going to go now? No idea.
If Nick Kyrgios can keep up this level then it is his match all day. But that's a big 'if'...
While Humbert goes to clear his head in the loo, Kyrgios has a laugh with one happy fan behind the baseline. I think he might have asked for a selfie!
David Law
BBC Radio 5 Live Sports Extra tennis commentator
Wow! What a moment. Nick Kyrgios comes back from the brink! This is not a case of Humbert choking. Kyrgios took the match from him. It is as good as it gets in terms of watching live sport.
Kyrgios 5-7 6-4 3-6 7-6 (7-2) Humbert
But he nails the second serve down the middle!! Stunning stuff from Nick Kyrgios.
This is sport, people.
We're into a fifth!!
*Kyrgios 5-7 6-4 3-6 6-6 (6-2) Humbert
Humbert saves one. And then there are a few groans after Kyrgios hits the net with a first serve...
*Kyrgios 5-7 6-4 3-6 6-6 (6-1) Humbert
Five set points...
Kyrgios 5-7 6-4 3-6 6-6 (5-1) Humbert*
This is the calmest we've seen Kyrgios in a while. The only other person equally calm is his dad George. Another stunner puts him within touching distance...
David Law
BBC Radio 5 Live Sports Extra tennis commentator
This is just incredible. I feel quite emotional watching this.
Kyrgios 5-7 6-4 3-6 6-6 (4-1) Humbert*
Now he's well in control. Buoyed by the partisan crowd, Kyrgios forces Humbert back behind the baseline and into two wayward returns.
*Kyrgios 5-7 6-4 3-6 6-6 (2-1) Humbert
Woof! A fizzing forehand has too much topspin and direction for Humbert to catch. Mini-break for Kyrgios...
Anne Keothavong
Former British number one on Tennis Breakfast
I've never seen Nick Kyrgios smile before! He's lapping up the love.
Kyrgios 5-7 6-4 3-6 6-6 (1-1) Humbert*
First blood to Kyrgios, who is reminding us why he loves playing in front of crowds.
Humbert responds before his next serve hits the net and is greeted by applause...
Anne Keothavong
Former British number one on Tennis Breakfast
Is Nick Kyrgios able to come up with something special here? I just don't know...
Kyrgios 5-7 6-4 3-6 6-6 Humbert
Let's see if Humbert can regain his focus. Before that last service game he was unperturbed.
He's back at his previous level, some solid serving helping him hold.
A one-way ticket to Tiebreak Town please...
David Law
BBC Radio 5 Live Sports Extra tennis commentator
What a match.