And just like that, it's 30-30.

Delicate hands from Nick Kyrgios, though, he pops a backhand winner with a straight racquet like he's playing a game of beach tennis.

Dimitrov scrambles for deuce, but Kyrgios gallops towards the net to smash out some frustration and take advantage, before holding serve.

Piers Newbery
BBC Sport at Melbourne Park

The stringer is shown working furiously on Kyrgios's racquet somewhere in the depths of Rod Laver Arena, while the man himself toils up above. It's the Dimitrov racquet that Kyrgios should be more concerned about right now as the Bulgarian is really looking the part.

Meanwhile, coach Dani Vallverdu tries to point out to the umpire that Kyrgios is engaged in a constant conversation with his player box. It's not exactly helping at the moment.

Nick Kyrgios serving to stay in the set.

He takes a 30-0 lead as Grigor Dimitrov goes long, but then gets called up for a foot fault and that brings up a double fault.

"I never foot fault in my life!" he says. "It's where it starts, Nick," responds the umpire.

He's chatting away, Kyrgios...

The Australian needs to regather some composure for the Dimitrov serve.

He can't, his shots are looking more and more sloppy and Dimitrov storms into a 40-0 lead.

The Bulgarian holds after Kyrgios cracks the net with a jumping half-volley.

The Bulgarian only needs one.

A lethargic, frustrated looking volley sails far too deep from Kyrgios and it's Dimitrov who snaffles the advantage in this second set.

Image source, AFP

Kyrgios whips a forehand well wide, his range has been pretty good today, but the sight was slightly out for that one.

Another through-the-legs shot follows! Exhibition stuff from Kyrgios to meet a dinked Dimitrov lob, but the Bulgarian is lurking at the net to finish it off on the volley.

Two break points for the third seed.

That was delicious from Nick Kyrgios, taking the Dimitrov serve outrageously early on his backhand and tickling it inside the line.

He sends another curling winner down the forehand side this time with the Bulgarian approaching the net.

It's called out, he challenges... it's narrowly wide!

And Dimitrov holds.

Grigor Dimitrov can't lift a forehand on the run high enough to beat the net, but wrongfoots Nick Kyrgios after scrambling around a high, bouncing ball to take it on the forehand side.

He follows up with an ace - 30-15.

Another big serve from Kyrgios, another big hold for the Australian.

Straight out of the sweet spot of Nick Kyrgios' racquet for his 17th ace of the day.

He drags a forehand wide off the next, before another cracking serve that just clips the frame of Dimitrov.

The Bulgarian goes long with a lobbed attempt, but pulls back to 40-30 with a well-placed forehand winner.

Image source, AFP

Piers Newbery
BBC Sport at Melbourne Park

Double faults and dodgy backhands had been the hallmark of Dimitrov's 2018 Australian Open, until tonight. The second serve still looks a little wobbly and there have been five double faults already, but off the ground he has looked much improved - just four unforced errors on the backhand in a set and a half.

Double fault, and a second deuce.

Is Grigor Dimitrov beginning to waver? Nick Kyrgios is yet to earn a break point, and still the wait goes on as the Bulgarian gets the better of the rally.

Ace. And the third seed holds.

Now it's Dimitrov showcasing his repertoire. Forcing Kyrgios one way and then the other, before delivering the sucker punch.

He eases into a 40-30 lead, before catching the tape with a loose forehand.

Deuce, and one that gets the crowd roaring again.

Magnificent from Kyrgios. Almost exactly the same spot, this time after Dimitrov failed to get enough purchase on a volley from midcourt.

His return on the Bulgarian's second serve goes long - that's 15-30.

Kyrgios opts for his towel, wiping away a few beads of sweat before the Dimitrov serve.

And the Australian shows off his arsenal with a slice that draws Dimitrov in, before beating him down the line with a thumping backhand winner.

A twirl of the finger to celebrate.

Nick Kyrgios is getting a little rattled, if another outburst is anything to go by.

He isn't fazed for long, a huge ace to regain focus and a sliced backhand that flops just over the net to follow.

He holds.

Image source, AFP

Nick Kyrgios whips one of those trademark curling forehands into the corner, Grigor Dimitrov can only find the net with his response.

The Bulgarian pulls it back to 15-15, engages Kyrgios from the next serve, but goes long.

Wonderful backhand, sliced volley winner from Grigor Dimitrov, like a ballet dance - arms outstretched, twirling towards the net.

Mind you, in that salmon outfit and standing on one leg, he almost resembles a flamingo too.

A double fault follows. But that's the only blemish on the Dimitrov serve.

Leon Smith
GB Davis Cup captain on BBC Radio 5 live sports extra

Dimitrov has looked brilliant from an emotion and mentality point of view. He has been in control and hasn't panicked even when he was not getting near the Kyrgios serve.

He is in a good place. He has struggled in a few matches but the conditions were so up and down and he managed to get through.

Nick Kyrgios carries on the big-serving exchange from the off in the second set.

He shows off his deft hands too, gliding towards the net and disguising a delicate drop shot just over the tape.

That's the hold. Clinical.