Good morning, and welcome to Australia Day on Rod Laver Arena, where the Victoria Opera Youth Chorus are singing Advance, Australia Fair acapella before the emergence of world number one Ashleigh Barty and her challenger Alison Riske of the USA.

"I love Petra, but let's hope she doesn't break my heart on Tuesday!" Ash Barty muses about her next opponent, the woman who beat her last year.

Alison Riske is going to be really diaappointed with that. What a way to lose. Barty, meanwhile, has ground out the win that everyone in Melbourne wanted.

BARTY 6-3, 1-6, 6-4 RISKE: Barty returns the pressure on Riske, who nets what looks like a simple shot. The American then tries to compose herself to deal with the first match point of the night...and double-faults. Game, set, match Ashleigh Barty.

BARTY 6-3, 1-6, 5-4 RISKE: Barty is moving much better than she was in that sluggish second set. A couple of great points here - Riske puts in a challenge on game point just for the heck of it.

BARTY 6-3, 1-6, 4-4 RISKE: Riske is on a roll, three games in a row to level this deciding set. She's putting the pressure on Barty.

BARTY 6-3, 1-6, 4-3 RISKE: Barty rolls her eyes as she challenges a Riske shot that landed just on the line - clearly more in hope than expectation from the world number one there. Then a wild forehand from Barty flies wide to give Riske a break back.

BARTY 6-3, 1-6, 4-2 RISKE: Hold for Riske to stay in touch.

BARTY 6-3, 1-6, 4-1 RISKE: Barty absolutely blasts her way through her service game to hold to love and put herself in the commanding position in this decider.

BARTY 6-3, 1-6, 3-1 RISKE: Ashleigh Barty needs to get her head in the game. Riske is very fortunate to benefit from a net cord bounce that the Australian doesn't bother moving for. It seems to galvanise her a little bit and she gets herself two break points - and takes the first brilliantly.

BARTY 6-3, 1-6, 2-1 RISKE: Barty keeps her nose just in front but this is ridiculously close, too close to call now. Riske has that psychological edge of the head-to-head dominance as well.

BARTY 6-3, 1-6, 1-1 RISKE: Riske holds to love, and the Rod Laver Arena crowd is subdued. Barty's coach Craig Tyzzer has his jaw clenched.

BARTY 6-3, 1-6, 1-0 RISKE: Good hold for Barty, who's still looking incredibly uncomfortable.

BARTY 6-3, 1-6 RISKE: Great comeback from Riske to force a decider after such a one-sided first set, and Barty has some real questions to ask herself as she takes to her chair.

BARTY 6-3, 1-5 RISKE: Barty looks slower than she was half an hour ago, and she's getting frustrated with herself. Riske is going to get the chance to serve this out.

RISKE 6-3, 1-4 RISKE: Barty is returning to the tactic that served her well in the first set, sending the ball to the corners and forcing Riske to the wings. She's not using consistently enough to break though.

BARTY 6-3, 1-3 RISKE: Well, Barty certainly needed that. A group of fans start to sing "Everybody (Backstreet's Back)" with the amended lyrics "Barty's back - ALL RIGHT!"

BARTY 6-3, 0-3 RISKE: Well, Riske is flying at the start of this second set. Her game isn't that much different but Barty's is just crumbling.