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
Nadal 6-3 6-4 5-5 Mayer
Mayer refuses to let Nadal sweep over the line, creating two break points and taking the second with a majestic cross-court backhand that leaves the world number one rooted to the spot and we're back on level terms in the third set.
It's not over yet...
Kyrgios v Troicki
Does the name Viktor Troicki ring a bell?
This might jog your memory...
Viktor Troicki's meltdown
Obviously, he's got some other credentials too.
The Serbian is looking for his 50th Grand Slam win today. This is his 10th Australian Open appearance and his 36th major.
Troicki, world number 65, is bidding to reach the third round here for the fourth consecutive year and equal his best Australian Open result.
He has three titles to his name, one fewer than today's opponent Nick Kyrgios.
Over on Margaret Court Arena, French Open champion Jelena Ostapenko has progressed to the third round after beating Ying-Ying Duan of China 6-3 3-6 6-4.
And world number one Rafael Nadal is one game away from a straight-set win over Leonardo Mayer on Rod Laver Arena.
On Hisense, Nick Kyrgios and Viktor Troicki are about to get under way.
Image source, AFPAs with every Grand Slam, better get there sharpish if you want to snaffle a ticket on the day.
The queues were building bright and early at Melbourne Park.
Kyle Edmund spoke to our tennis correspondent Russell Fuller after his second round win.
"It was good. It was hotter today so after four hours on court on Monday, it was good to get on and off," said the 23-year-old Briton.
"At a Slam any moment to have a rest is good. Today I was professional and managed the game well. I shut him out on my serve and didn't give him a sniff. Overall I'm happy with how things went on court.
On being the highest ranked player in the open section of the draw: "I haven't seen the draw and I know who I play next. You know who's playing who, who's winning and losing, but there's no point in looking ahead if you cant get past the guy in front of you."
On dealing with the heat: "The only way to get better at playing in the heat is by doing it. My trainer comes up with the best things for me, and every individual is different. The way I play is explosive with power, so we do short stuff as hard as we can. Being smart with you work is key to improving."
Image source, Getty ImagesThere was plenty of drama in the day session in Melbourne.
Head over to our Tennis page for more results.
Image source, Getty ImagesOn the big stage (Rod Laver Arena), it's ATP finals winner and third seed Grigor Dimitrov against world number 178 Mackenzie McDonald of the USA.
On the slightly smaller stage (Hisense Arena), it's Aussie Nick Kyrgios against Viktor Troicki.
We'll bring you updates from both second round matches, plus the best of the rest from around the courts in Melbourne - including Jamie Murray in the doubles.
You can also listen on BBC Radio 5 live sports extra by clicking the icon at the top of this page.
Image source, Getty ImagesMorning!
Or evening.
Or g'day.
Let's just say 'welcome' to cover all bases. Ready for some more heavy hitters?
Image source, Getty Images
Image source, Getty ImagesBut with British number two Kyle Edmund safely through to the last 32 after an impressive straight-set win against Denis Istomin, it's time for us to take a breather.
Grab a cuppa, have a snooze, but whatever you get up to, don't forget to tune back in for Tennis Breakfast on BBC Radio 5 live sports extra from 07:00 GMT.
We'll also have live text commentary of third seed Grigor Dimitrov's second-round outing against American Mackenzie McDonald.
Plenty to whet your appetite from day three in Melbourne...
Meanwhile, a few scores to keep your eye on...
Jana Fett took the first set 6-3 against Caroline Wozniaki, before the Dane won the second 6-2.
Fett is currently 1-0 up in the final set on serve.
We mentioned Denis Shapovalov earlier, and the Canadian is currently leading Jo-Wilfried Tsonga 6-3 3-6 6-1 5-5.
Stay across the BBC Sport website for reports on those two matches, as well as top seed Rafael Nadal's upcoming second-round meeting with Argentina's Leonardo Mayer.
Kyle Edmund goes on to face world number 61 Nikoloz Basilashvili of Georgia next.
The 25-year-old beat Belgium's Ruben Bemelmans 7-5 6-1 6-3 to progress.
Edmund 6-2 6-2 6-4 Istomin
More from Kyle Edmund, who says he took confidence from his first-round five-set victory against 11th seed Kevin Anderson into the meeting with Denis Istomin.
He certainly looked in great form on court 13, seeing off the Uzbek 6-2 6-2 6-4 to reach the last 32.
"It gives you confidence beating a guy like Anderson," added Edmund. "So today I took confidence knowing physically I stood up and my level was good.
"I knew going into the match I was in a good place."
James Stevenson: Job done. Never in trouble. Kyle Edmund looks like he could make quite a bit of progress at #AusOpen, external 2018. On to the next one.
Piers Newbery
BBC Sport at Melbourne Park
Thirteen service games without facing a break point and job done in 89 minutes - that goes down as a pretty faultless way to win a Grand Slam match. Edmund lost just three points behind his first serve, something he worked on in the off-season, and once again the forehand dominated among 38 winners. He will face much tougher tests if he is to go really deep but the basics of his game are looking very solid.
And here is Kyle Edmund: "There is always that danger of someone like Denis coming back - you saw what he did here last year (knocking out Novak Djokovic).
"It was a professional performance and doing it quickly will do me good.
"The plan is to get through, whatever it takes - if it takes three or four hours then so be it, but it's perfect really."
Tennis coach David Felgate on 5 live sports extra
Really impressive victory. The reaction at the end me tells me a lot. He knew he needed to back it up and that was quite exuberant for Kyle. Forehand, backhand, serve - job done. He was very good right from the get-go.
Edmund 6-2 6-2 6-4 Istomin
Image source, Getty ImagesThat's it! Kyle Edmund sees off Denis Istomin in three sets.
Edmund fizzes a punishing forehand in to seal the match after a high Istomin return to the back of the court.
He's through to the last 32, and in impressive fashion.
*Edmund 6-2 6-2 5-4 Istomin
Right then, Kyle Edmund is within touching distance of the third round...
First serve down, and it's a good one, too hot for Denis Istomin to handle.
The Uzbek can't get his return on target from the next point either - 30-0.
*Edmund 6-2 6-2 5-4 Istomin
Istomin rattles through his service game to make Edmund serve for the match.
Talking of serves, just what is Judy Murray's lunch being dished up on?! That's one oversized plate...
Andy Murray has had some cutting remarks for mum Judy over lunch...
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