An instant break back? That's exactly what the tennis doctor ordered. 

Heather Watson wrestles two break points from Timea Babos, who then decides to go for broke with two massive forehands down the line.

Deuce. Watson goes on the attack, charging into the net, unsettling Babos who misses the line.

Ooof! Take that. Gutsy play by Watson who hammers a backhand back at the Hungarian - and she can't deal with it.

We're back on serve...

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

"Heather must have been very clear that ball was long. But when you're desperate to win the point, sometimes you can see something that isn't there. That's a big moment, because she was on top in that point."

Oh no! Heather Watson looks crestfallen as she pulls out of a shot to challenge a Timea Babos forehand on the third break point. Watto thinks it is long, Babos looks confused. And Watto is wrong - Babos wins the point and the break. Big turning point.

First break point for Babos....disappears. The Hungarian spanks a forehand down the opposite line...is it in?! Nope. The ball just misses the whitewash.

Break point two? Also goes begging! Watson forces Babos into a wayward forehand and wriggles out of tight spot.

Watson finds herself in deep trouble. Her first serve goes missing, leading to a 30-0 advantage for Babos

Then the Briton manages to turn defence into attack, forcing Babos to crack a forehand into the net for 15-30.

That should give her a boost but then, rather inexplicably, Watson slaps a backhand volley into the net. That's two break points for Babos...

"Aaaargh!" Heather Watson screams out, slapping her left thigh in frustration.

That's because she looked to be on top in a rally at 40-30 on Timea Babos' serve, only to blow her chance of forcing deuce by drilling a forehand into the tramlines. 

Babos sighs with relief - she knows she has been let off the hook.

*denotes next serve

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

"Generally speaking, it's better to serve first in the final set, to be ahead and pile the pressure on your opponent to stay in the match. Babos has a good first serve and that's going to help her. She had a 70% first serve in that second set, and that's excellent for someone who's really going for it."

Luke Jones: Heather needs aggressive body language: lots of jumping on the spot, fist pumps and lots of noise! Take momentum away from Babos.

Heather Watson looks pretty unflustered as she serves for the second time in this deciding set. The Briton is chasing the set again - but it isn't a problem. Another impressive service game sees the Guernsey girl wrap up a hold to love.

Oooh hello! Heather Watson has a sniff of a break. The British number two forces Timea Babos into a pair of rogue forehands that fail to land where she intended. 

But that 30-0 lead for Watson quickly disappears down the plughole as Babos rattles off four straight points to hold.

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

"Good serving there from Heather. It's good to see she's got over the disappointment of losing the second set. She's making more balls and the footwork is back to being precise."

Any nerves that jangling inside Heather Watson's mind disappear after a routine hold. Now can she dig out a break and pile the pressure on the Hungarian??

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

"Watson will need to fight. She has good crowd support out there. She'll get energy from them, she'll get energy from Judy Murray. She'll make a lot of balls, extend the rallies and try to take Babos' legs away from her."

Testing times for Heather Watson. She bounds out of her seat for the deciding set - she loves a scrap, we know that.

The British number two makes a couple of inroads into the Babos serve, but not enough to threaten a break at the first attempt.

A sloppy forehand goes long as Babos waves a clenched fist at her team.

Alex Haworth: From 30-15 serving for the match. Watson won 2/14 points to surrender the set. What a choke.

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

"You can see the body language has changed with Babos. She's full of energy, she's doing the fist pumping and she's making every shot. Heather wasn't able to dominate on serve when she served for the set. From that moment, Heather's form and focus dipped a bit. Babos was fighting for every ball and ultimately applied too much pressure. She will have some good momentum going into the third set."

Oh no! What's happened here?! Heather Watson loses her way at the crucial point of the second set, allowing Timea Babos to tee up three set points.

A deciding set is looking inevitable, although the Briton staves off one of the set points. The Hungarian is not to be deterred, however, but Watson is the architect of her own downfall.

There's a gasp of horror from the predominantly Watson-supporting crowd as she smashes straight into the net to hand the second set to Babos.

Comfortable passage into round two for home favourite Nick Kyrgios...

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

"Momentum is talked about an awful lot. Things can change so quickly in this game. When Heather couldn't serve out the match, she needed to lock down and not give Babos an easy service game. But now the pressure is back on Heather."

My word - Timea Babos has a set of lungs on her. The Hungarian lets off some steam with a loud roar when she breaks back - most of Melbourne will have heard her. She mops up an easy hold in the next game to pile the pressure back onto Watson.