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
*Kyrgios 7-5 1-0 Troicki
Oooh, Viktor Troicki's not happy.
The Serbian is broken in the first game of the second set and he angrily slams the ball into the top deck of the Hisense Arena.
Behave, you.
Dimitrov v McDonald
Grigor Dimitrov has never lost to a qualifier at the Grand Slam, and in eight meetings with qualifiers he has dropped just one set against.
Trying to change all that today is American Mackenzie McDonald.
This is the 22-year-old's second appearance at a Grand Slam, having made his debut at the 2016 US Open.
McDonald defeated qualifier Elias Ymer 6-4 6-3 4-6 6-1 in the first round on Monday to record his first Tour-level match-win.
Third seed Dimitrov is the highest-ranked player that McDonald has ever played against. Gulp.
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Mark Woodforde
12-time Grand Slam doubles champion on BBC Radio 5 live sports extra at Melbourne Park
That was a bit of cat and mouse from Kyrgios. He changed the pace of his shots and waited for an opening and then it came with that drive up the line and he put his full weight into the winning shot. His shots are full of disguise.
Kyrgios 7-5 Troicki
BOOM! Kyrgios' ninth ace of the match sees him hold to love and take the first set in style.
He looks super confident out there and the home crowd are very much behind their boy.
Dimitrov v McDonald
Is Grigor Dimitrov finally living up to the 'Baby Fed' tag he was awarded when he first came on the scene?
After a three years without silverwear, the Bulgarian won four titles in 2017, including the ATP Finals in London.
Now at the highest ranking of his career, the world number three is searching for his first Grand Slam title.
Last year in Melbourne, Dimitrov equalled his best Grand Slam result by reaching the semi finals, where he fell to Rafael Nadal in five sets.
Image source, Getty Images*Kyrgios 6-5 Troicki
Three break points land in Nick Kyrgios' lap after consecutive double faults from Viktor Troicki.
A forceful backhand on the 22nd shot of the match's longest rally proves to be the winner - Kyrgios takes the game!
The Australian will serve for the set.
Kyrgios 5-5 Troicki*
Nick Kyrgios survives a testing a few minutes as his opponent threatens to make the first break of the match.
After much muttering and frowning, Kyrgios composes himself after deuce to hold and level the score again.
I love Judy Murray the most.
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*Kyrgios 4-5 Troicki
Viktor Troicki throws down his seventh ace of the first set as he holds again.
No breaks so far.
Having lost the first set 7-5, Britain's Jamie Murray and his Brazilian partner Bruno Soares have taken the second 6-4 in their opening doubles match against American pair Donald Young and Frances Tiafoe.
Find someone who looks at you like world number seven David Goffin looks at this koala.
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Kyrgios 3-3 Troicki*
Next up on Rod Laver, it's Grigor Dimitrov against qualifier Mackenzie McDonald.
Over on Hisense, it's going with serve between Nick Kyrgios and Viktor Troicki - although the Serbian had to fight off two break points in his opening game.
Nadal 6-3 6-4 7-6 (7-4) Mayer
Rafael Nadal speaking on court: "Important victory for me against a tough. Leo is a player with so much potential. I had to hit some great shots in the tie break to beat him. He's a tough opponent and I wish him all the best for the season.
"I'm happy to be in the third round. A second win in a row is important for me.
"Being here is a special feeling. the court is a massive motivation. It's been a long day and the crowd are still here, so many thanks."
Nadal 6-3 6-4 7-6 (7-4) Mayer
He's done it!
Rafael Nadal celebrates emphatically as he books his place in the third round for the 12th time in his career.
It's tough on Leonardo, who put up a fierce fight - even if it doesn't show on the scoreline.
Nadal 6-3 6-4 6-6 (6-4) Mayer
A booming ace - only his fourth of the match - moves Rafa Nadal closer to the third round.
But Mayer responds in kind with an ace of his own.
He thinks he's landed another one - only for it to be ruled out after a challenge.
Although the Argentinian closes the gap on his opponent, Nadal now brings up two match points on his own serve.
Nadal 6-3 6-4 6-6 (4-2) Mayer
"Vamos," screams Nadal as he jumps in the air and celebrates after a glorious backhand sends him further ahead in the tie-break.
Nadal 6-3 6-4 6-6 (2-1) Mayer
One massive overhead smash didn't quite go to plan so Leonardo Mayer has another go. This time it's too big and too far away from Nadal.
On the next point, Mayer's return is called out. It's challenged but to no avail. Nadal edges ahead.
Nadal 6-3 6-4 6-6 (1-0) Mayer
To answer that earlier question: no he can't.
Rafa Nadal holds to love and we go to a tie-break.
And the Spaniard makes a dominant start by snatching the first point off his opponent's serve.
Nadal 6-3 6-4 5-6 Mayer
Leonardo Mayer holds his serve for a 6-5 lead against the world number one.
Can he get a double break to take it to a fourth set?
Kyrgios v Troicki
For a while now, Nick Kyrgios has had a reputation as the Tour's "bad boy" - arguments with referees, sulking on court and slagging off fellow players.
But is that all in the past now? In several interviews building up to the Australian Open, the Canberra boy said he wanted to leave that life behind.
And 2018 has looked rosy for him so far. Kyrgios won his fourth career title – and his first on home soil – at Brisbane earlier this month, defeating Ryan Harrison.
He breezed into the second round in Melbourne after a straight-set win over Rogerio Dutra da Silva of Brazil.
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