Johanna Konta hasn't been able to open Bernarda Pera up on these past few points. The Briton catches the tape with a weak backhand from mid-court.

Two break points for Pera.

Oh dear. Another Johanna Konta double fault, the fourth of this second round match - she didn't make any in the opener against Madison Brengle.

Konta forces the powerful Pera to dart forward with a smart slice, and the American can only prod it long - 15-15.

Russell Fuller
BBC tennis correspondent at Melbourne Park

Konta is out of sorts and doesn't have any consistent answers to the questions Pera is posing.

Pera takes back control of her service game with some pacy groundstrokes that have too much whizz and bang for Konta - the American holds.

Piers Newbery
BBC Sport at Melbourne Park

After a drowsy feel to the opening stages of this morning kick-off, the crowd are waking up to the very real possibility of a significant shock unfolding before them. Konta has yet to hit an ace and is under a constant barrage of attacking returns from the impressive Pera.

LTA coach Jeremy Bates rests his chin on his hands, looking concerned. Although that might be sun-related, as he’s boldly gone for the sunny side of the stadium.

Good movement from Johanna Konta, squeaking across the court two surface, but Bernarda Pera pretty much published that sliced volley for the Brit.

Konta goes 0-30 up, but it's Pera who then comes out on top after a 13-shot rally.

Image source, Reuters

Maria Sharapova is closing on victory against Anastasija Sevastova, leading 6-1 4-3 with a break on Rod Laver Arena.

There's been a turnaround on the Margaret Court Arena - Dominic Thiem was 5-3 up against another American qualifier, Denis Kudla, - it's now 6-5 to Kudla who is about to serve for the first set.

That's a big, kicking first serve to force Pera wide and off target and a missed return from the American on the next point hands Konta advantage.

Another forceful serve from Konta in the Melbourne breeze proves too hot to handle for the world number 123 and Konta holds.

Double fault Johanna Konta. Break point Bernarda Pera.

Image source, Getty Images

Bernarda Pera is getting in front early on every Johanna Konta service game.

The British number one finds herself 15-30 down after another powerful Pera backhand return, before Konta responds with some firepower of her own, this time on the forehand side - 30-30.

Fantastic. Another thumping forehand winner from the world number 123, who beats Konta from her own baseline.

Pera holds.

Naomi Broady
British number three on BBC Radio at Melbourne Park

Konta's shots aren't hurting Pera as they usually do, I think it's because of the spin from the left-hander.

A third double fault in a row from Bernarda Pera gives Johanna Konta a welcome point, but the American scuttles back to 15-15.

The left-hander is putting everything into each forehand, and keeps Konta rooted to the baseline before approaching the net and patting a volley beyond the ninth seed.

Good recovery from Johanna Konta, who capitalises on a miss from Bernarda Pera.

The British number one sprints into the net with Pera on the run, but she dinks a drop shot over the net on the half volley with all the subtly of a lumberjack in a florists and Pera pounces.

The American breaks straight back.

Punchy stuff from Bernarda Pera, jabbing Johanna Konta one way and then finishing the point off with a hammer blow of a backhand the other.

Three break points for the American, she's certainly not fazed by that sloppy service game a moment ago.

Konta pulls back to 15-40.

Naomi Broady
British number three on BBC Radio at Melbourne Park

At the start of the second set, Jo has found her focus and Pera almost lost hers, two double faults in the game.

Two break points for Johanna Konta, her first of the game - and they come signed, sealed and delivered courtesy of a Bernarda Pera double fault.

Pera backs it up with another, and there's the break for Konta.

Image source, EPA

We've had freight trains, now it's police sirens on the Bernarda Pera serve.

The alarm bells may be starting to ring for Johanna Konta, she slips on the Melbourne Park surface and backs it up with an "oww".

But Konta is back on her feet.

Naomi Broady
British number three on BBC Radio at Melbourne Park

Great opening first service game for Konta, it shows her mental strength to regroup and stay calm and collected.

Better from Johanna Konta in the opening service game of the second set, looking for depth on her groundstrokes and making Bernarda Pera force the point.

She whips a big serve in to hold to love.