Grigor Dimitrov beats qualifier Mackenzie McDonald in five sets
Third seed wins 4-6 6-2 6-4 0-6 8-6
GB's Edmund through to third round
Kyrgios beats Troicki 7-5 6-4 7-6 (7-2)
Nadal beats Mayer in straight sets
Wozniacki saves match points on way to tough win
Jill Craybas
Former world number 39 on BBC Radio 5 live sports extra
I don't know much about Mackenzie McDonald to be honest. I've heard about him and that he's highly talented.
Having watched the first set, he's got a great serve and places it really well and I've been really impressed with how he's managing himself here on Rod Laver Arena.
Image source, AFPDimitrov 4-6 6-2 McDonald
A marketing email has just dropped into my inbox about Grigor Dimitrov's new partnership with a well-known ice cream brand.
If eating loads of sugary-sweet desserts is the way to get you into the world's top three then hand me a spoon.
Dimitrov 4-6 6-2 McDonald
Grigor Dimitrov's recovery continues.
He brings up three set points on Mackenzie McDonald's serve.
Two go amiss but the American scoops the ball over the baseline and the third seed bites back to level the tie.
Dimitrov 4-6 5-2 McDonald
Grigor Dimitrov has broken back against qualifier Mackenzie McDonald on Rod Laver Arena and has taken a commanding lead in the second set.
The Bulgarian third seed holds to 15 for a 5-2 lead.
Mark Woodforde
12-time Grand Slam doubles champion on BBC Radio 5 live sports extra at Melbourne Park
That felt almost like a five-set encounter. Trioicki threw everything at Kyrgios and overall Kyrgios responded well. He had his moments where he lost his way but in the end he played pretty well.
He expects to play almost near-perfect tennis but if the umpire doesn't live up to that same level he very quickly goes off on a tangent and becomes distracted.
In the past he might have lost matches because of that but hopefully now he can minimise the unhappiness and the complaining and keep winning these matches.
He thrives on playing the favourites. He doesn't feel scared where sometimes he might feel that way against players he should beat.
Kyrgios 7-5 6-4 7-6 (7-2) Troicki*
It's all over. Another straight-set win for the Australian favourite.
What with crowd disturbances, helicopters, broken umpire mics and broken umpires, it was fairly eventful.
*Kyrgios 7-5 6-4 6-6 (6-1) Troicki
Troicki slams the hard court with his racquet in anger as Nick Kyrgios moves 4-1 up.
The Australian is back on serve. Troicki goes for a big return and BANG.
Oh. My. Word. He's hit the chair umpire on the head with an almighty hit! That's gotta hurt. James Keothavong manages to laugh it off like a champ.
"It's not been my day, has it?" he jokes.
Meanwhile, Kyrigos has five match points...
Kyrgios 7-5 6-4 6-6 (2-1) Troicki*
First blood: Nick Kyrgios.
The Australian snatches the first point from Viktor Troicki's serve.
But a backhand falls outside the mark - it's 1-1.
A moment of magic from Kyrgios puts him ahead again. A beautiful strike down the line. Love that.
*Kyrgios 7-5 6-4 6-6 Troicki
Right then, you lot. Nick Kyrgios holds his serve so it's tie-break time on Hisense Arena.
Try to keep up.
Mark Woodforde
12-time Grand Slam doubles champion on BBC Radio 5 live sports extra at Melbourne Park
Kyrgios has lost his way and isn't playing with any real intent. These are the moments you'd love to listen into the brain of players at changes of end to hear what they're thinking.
Image source, AFP*Kyrgios 7-5 6-4 5-6 Troicki
Hummm, yeah. Nick Kyrgios' head has gone a bit here.
A couple of errors from the Australian sees Serbian Troicki hold.
And now the 17th seed has to serve to stay in the third set.
David Law
Radio 5 live sports extra commentator at Melbourne Park
How can a straight-set match be so stressful? Everyone seems stressed. I feel stressed.
Kyrgios 7-5 6-4 5-5 Troicki*
After losing the first point, Nick Kyrgios breaks down Troicki's favoured backhand to level at 15-15.
An ace brings the Australian to 30-15 but then he shoots long. We're even again.
Troicki earns a break point thanks to a net cord. And he's taken the game!
Well, well,well. What a time to drop your first service game.
*Kyrgios 7-5 6-4 5-4 Troicki
Here we go. Nick Kyrgios has a break and a match point...
Ah, it's gone. Viktor Troicki dinks over and we go to deuce.
A blistering serve from Troicki sees him through the game and Kyrgios will now serve for a place in the third round.
Dimitrov 4-6 McDonald
Mackenzie McDonald has three set points. Marvellous from the young American qualifier!
Two go to waste. Can he sow it up at the third attempt? Yes he can!
A big serve overpowers Grigor Dimitrov and the third seed is a set down.
Upset on the cards?
*Kyrgios 7-5 6-4 4-3 Troicki
Now it's fist pump time for Viktor Troicki as he holds his serve to keep in touch with young Nick Kyrgios.
He needs a break, though, and he needs it fast.
Dimitrov 3-5 McDonald
Qualifier Mackenzie McDonald earns himself a fist pump as he fends off two break points from third seed Grigor Dimitrov.
Dimitrov nets to hand McDonald the advantage after deuce and the American holds after another error on the backhand from the Bulgarian.
Mark Woodforde
12-time Grand Slam doubles champion on BBC Radio 5 live sports extra at Melbourne Park
There's so much pent-up frustration and nervous tension coming out. It's like he's won the match but he's only broken serve. If he could just contain himself now and draw a line under this it would help him.
Kyrgios 7-5 6-4 2-1 Troicki
Nick Kyrgios continues to lead the way on Hisense.
The 17th seed moves ahead with a break in the third - and possibly final - set against a stuttering Viktor Troicki.
Dimitrov 2-4 McDonald
Over on Rod Laver Arena, young Mackenzie McDonald is still holding his own against the 2017 end-of-year champion Grigor Dimitrov.
The American broke in the third game and now leads 4-2 against the Bulgarian third seed.
Image source, Getty Images