France are one win away from claiming the Fed Cup title after Kristina Mladenovic broke Australian hearts with a stunning 2-6 6-4 7-6 (7-1) win over world No.1 Ashleigh Barty in Perth.

Barty's 15-match Fed Cup winning streak came crashing to a halt as Mladenovic mounted a lion-hearted comeback to prevail in two hours and 31 minutes and put France up 2-1 in the best-of-five rubbers final.

The loss means Australia's Ajla Tomljanovic must defeat Pauline Parmentier in Sunday's second reverse singles match to force a doubles decider. France opted to bring in world No.122 Parmentier as a substitute for Caroline Garcia, who Barty thrashed 6-0 6-0 in Saturday's singles rubber. Mladenovic was struggling for words and in tears after claiming the biggestvictory of her career.

"It's tough to speak," the Frenchwoman said.

"We kept on fighting every single point. That's the way I love to play my tennis ... I just kept believing."

Barty had gone into Sunday's match at RAC Arena as the hot favourite after her annihilation of Garcia the previous day.

But world No.40 Mladenovic again proved too good, storming back from being a set down to consolidate her defeat of Barty on clay in Rome six months ago. In a match full of momentum swings, Barty rode a wave of support from the near- capacity crowd to go up 6-5 in the third set.

But the equally determined Mladenovic served to love and didn't blink during a ruthless tiebreaker.

Barty will be left to lament an uncharacteristically wayward performance in which she made 47 unforced errors.

The French Open champion came out firing with back-to-back aces to take the first game, then broke Mladenovic's serve beforetaking the first set in 33 minutes.

But the French No.1, who thrashed Tomljanovic 6-1 6-1 on Saturday, forced her way back into the contest and consolidated inan epic 66-minute deciding set.

Earlier today, Barty said she had learned plenty about her French opponent from the 6-2 6-3 defeat on clay six months ago in Rome.

"Having played her in Rome earlier this year, I know that she has the weapons to be able to make me uncomfortable," Barty said.

"So it's about trying to nullify those as best as I can and bringing it back to my tempo of match.

"I feel that I've changed and developed as a person and player since that match in Rome.

"I'm really looking forward to it tomorrow to try and turn the tide a bit."

FIXTURES/RESULTS

Saturday

Kristina Mladenovic defeated Ajla Tomljanovic: 6-1 6-1

Ash Barty defeated Caroline Garcia: 6-0 6-0

Sunday

Kristina Mladenovic defeated Ash Barty: 2-6 6-4 7-6

Ajla Tomljanovic vs Caroline Garcia

Ash Barty/Sam Stosur vs Caroline Garcia/Kristina Mladenovic

- with AAP