Ashleigh Barty’s brave bid to end Serena Williams’ grand slam comeback ended in a thrillling, three-set French Open defeat for the Australian No.1.

Barty appeared to be careering towards a famous victory Friday morning (AEST) before letting slip a one-set advantage in the 3-6 6-3 6-4 second-round loss at Roland Garros.

Seemingly unaffected by the occasion, Barty broke the 23-time major champion early in the second set to surge further ahead before Williams willed her way back into the enthralling contest on Court Philippe-Chatrier.

Barty’s game plan to move Williams from side to side in the hope of exhausting the underdone champion in just her sixth match back since giving birth last September initially paid dividends.

But the grand slam colossus drew on her unrivalled fighting qualities – and energy reserves many doubted she still possessed at almost 37 and eight months into motherhood – to stave off Australia’s 17th seed after one hour and 46 minutes.

“I lost the first set, and I thought, ‘I’ve got to try harder. I’ve got to just try harder.’ And Serena came out,” Williams told the crowd before breaking into relieved laughter.

“Every day is a great day for me. I’m going to be here, fighting my heart out. It’s such a great feeling,” she added.

Barty’s exit leaves former finalist Samantha Stosur and 24th seed Daria ‘Dasha’ Gavrilova to fly the Australian flag.

Daria Gavrilova showed her fighting spirit to win through to the round of 32 at Roland Garros. Photo: AAP

Gavrilova cashed in on a stunning meltdown from Bernarda Pera to scrape into the French Open third round in Paris.

The 24th seed teetered on the brink of a humbling straight-sets exit before saving a match point with a 2-6 7-5 6-3 Houdini act.

Pera collapsed dramatically after blowing a match point at 5-2 up in the second set.

The American again served for the match at 5-4, but was unable to land a ball in the court, the left-hander incredibly committing nine unforced errors in a row, including a double-fault, to gift Gavrilova a lifeline.

Gavrilova didn’t immediately capitalise on her unexpected good fortune, dropping serve to love in the opening game of the third set and falling behind 2-0.

But she quickly regrouped and reeled off five straight games before clinching an epic victory after two hours and 35 minutes.

The great escape followed a similar fightback win from a set and a service break down in the first round against Sorana Cirstea and thrust Gavrilova into a showdown with Australian Open semi-finalist Elise Mertens on Saturday.

Gavrilova joins Stosur in the final 32 after the veteran clay-court star ruthlessly downed doubles partner Anastasia Pavlyuchenkova 6-2 7-6 (7-0) to set up a third-round match against 2016 champion Garbine Muguruza.

-with AAP