Postpublished at 00:36 Greenwich Mean Time 21 January 2020
*Konta 4-6 1-4 Jabeur
Right, Johanna Konta needs to find some momentum now.
There's better placement on the British number one's serve as she edges to 30-0.
Briton Harriet Dart wins final-set tie-break to beat Misaki Doi & reach second round
GB's Johanna Konta, Kyle Edmund, Cameron Norrie & Katie Boulter all beaten
Rafael Nadal, Danill Medvedev, Nick Kyrgios into second round
Simona Halep & Karolina Pliskova advance but Maria Sharapova loses
Heather Watson's match pushed back to Wednesday
Day two of Australian Open in Melbourne
Listen to Tennis Breakfast on BBC Radio 5 Live Sports Extra - press play button at top of page
Amy Lofthouse and Alex Bysouth
*Konta 4-6 1-4 Jabeur
Right, Johanna Konta needs to find some momentum now.
There's better placement on the British number one's serve as she edges to 30-0.
*Konta 4-6 1-4 Jabeur
Ons Jabeur goes through the gears to hold and consolidate that break.
Konta 4-6 1-3 Jabeur*
Johanna Konta looks to move the world number 78 across the baseline but has to go dashing forward to meet a deft drop shot. Good hustle from the Brit, 30-30.
Naomi Broady
British player on BBC Radio 5 Live Sports Extra
Jo has got a lot of work to do, she really has to settle down. Maybe she needs to mix up the placements on her second serve.
Konta 4-6 1-3 Jabeur*
And Jabeur breaks!
Three games in a row for the Tunisian as she takes the advantage in the second set.
*Konta 4-6 1-2 Jabeur
Talking of that return... a hammer of a backhand down the line brings up two break points.
*Konta 4-6 1-2 Jabeur
Ons Jabeur's slightly unconventional and unpredictable style is keeping Johanna Konta guessing and causing her some problems, the Tunisian's big return is also an issue for the British number one. 15-30.
*Konta 4-6 1-2 Jabeur
Ons Jabeur backs up that break back with a love hold.
Naomi Broady
British player on BBC Radio 5 Live Sports Extra
Such a good response from Jabeur there. Both of them so far in this set have really stepped up.
Jonathan Jurejko
BBC Sport at Melbourne Park
First rule of tennis club: hold after breaking serve.
Konta 4-6 1-1 Jabeur*
No way! Ons Jabeur, on break point, opts for the most delicate of drop shots and comes up trumps... a scrambling Johanna Konta can't stick a string on it.
The Tunisian breaks back immediately.
*Konta 4-6 1-0 Jabeur
Johanna Konta saves the first, one more to go.
*Konta 4-6 1-0 Jabeur
That's postage-stamp stuff from Ons Jabeur, finding the corner with a forehand.
Break back points...
Jonathan Jurejko
BBC Sport at Melbourne Park
That's more like it Jo! And the applauding and whooping Brits agree.
Konta comes out from the changeover like a boxer looking to make amends after getting a bloody nose in the previous round.
But now Jabeur is punching back...
*Konta 4-6 1-0 Jabeur
Ons Jabeur is gobbling up those slower second serves by Johanna Konta, another one disappears past her before the Brit can blink.
Jabeur edges to 0-30 before Konta zips in a kicker of a first serve.
*Konta 4-6 1-0 Jabeur
Punchy stuff from Johanna Konta as Ons Jabeur drives a forehand into the gauze.
The Brit breaks, with a little "come on!" to boot.
Konta 4-6 0-0 Jabeur*
Lovely, sweeping winner from Johanna Konta to steady the nerves early in the second set.
The British number one meets a volley at the net and that's two early break points.
Naomi Broady
British player on BBC Radio 5 Live Sports Extra
When Jabeur is under pressure, she starts to be more aggressive.
Jo is just not quite hitting her targets. She's got fewer winners and more unforced errors. She's not played many matches this year, so it's not a shock if she's not match tight and may start to settle a bit.
A lot of the times Jo was trying to go near the lines, she just missed them.
Jonathan Jurejko
BBC Sport at Melbourne Park
Johanna Konta had not faced a break point since the opening game and when she faced another it came at a critical time.
The Brit's first serve let her down when she needed it most and Jabeur punished her.
Konta 4-6 Jabeur
And what a forehand winner that is from Ons Jabeur... skipping across the baseline to sling it down the channel and leave Johanna Konta stranded.
The Tunisian takes the opening set.