Thumping return from Kenin. She's got a break point!

Forehand down the line from Barty... long!!

Deuce.

Some of the crowd think it's an ace. It's called out.

Kenin saves the first set point with a drop shot then a volley at the net. Nice!

Kenin's backhand goes wide. 15-0.

Her next return falls into the net. 30-0.

Kenin picks out the lob and volleys it out of Barty's control. 30-15.

A deep forehand is out of reach of Kenin.

Here come two set points.

Barty to serve for the set and to level things up.

Much better from Kenin, who does superbly well to win the rally with a range of shots. Barty's backhand slice then curves wide.

She's hanging in the second set. Can Barty hold her nerve to see it out?

Kenin races to 30-0 but pulls another forehand wide. Her dad tries to calm her down from the box.

It doesn't work. 30-30.

Image source, AFP

Barty moves up to 30-0 before Kenin successfully challenges a long backhand. The American then skews one down the line and is clearly annoyed at herself.

It's just not happening for either of them, though Barty is starting to find her backhand. She holds comfortably and looks more confident.

The American holds as Barty hooks a backhand into the net. Still very tight!

She's starting to turn it up... Barty smashes a forehand winner into the corner. Kenin responds with a big serve down the T and a fist pump.

The American moves up to 40-15 with some more decent serving but drags a backhand wide. 40-30.

Kenin's forehand is short and Barty makes the most of it. The Aussie then pulls off a superb backhand slice down the line - incredible!

Another one follows! Two brilliant backhands. Where did they come from?! She holds and shouts "come on!" for the first time. That's more like it.

Jonathan Jurejko
BBC Sport at Melbourne Park

Update on the heat levels. The Aussie Open stress scale is up to 4.8. Which means it is edging closer to the Laver roof being closed...

Better from Barty, who reads the drop shot and volleys away the lob. But she follows it up with a loose backhand.

A big serve is returned into the net and a nice from drop shot from Kenin does the job.

Kenin's return drops long. 30-0. And another one. 40-0. Then that slice backhand from Barty falls into the net again. 40-15.

Barty's forehand into the cords now. 40-30... But a big serve is hit straight back into the net from Kenin.

New balls for Barty. She hits an ace with the first one.

She's got it! Kenin hooks a backhand over the baseline. Big break for Barty, who needs to use this momemtum now.

How will Kenin respond?

Kenin serves wide to Barty's forehand and she smashes it straight out. 30-15. Barty responds with a nice forehand down the line. 30-30.

A sliced backhand then finally comes off for Barty and she opens up a break point.

You can sense the tension in Melbourne.

"Come on, Barty," a local screams.

A backhand slice from Barty rolls into the net. Kenin overcooks a forehand. Another return goes wide.

Barty then hits a sweet forehand winner and another big serve helps her out. Comfortable hold.