Strasbourg, France, 28 May 2017 | AAP

Sam Stosur has denied Daria Gavrilova in an epic three-set final in Strasbourg to retain her Australian No.1 ranking and claim the ninth title of her celebrated career.

In a major French Open boost for the former Roland Garros runner-up, Stosur recovered from a set down to defeat Gavrilova 5-7 6-4 6-3 in the first all-Australian women’s tour final in 12 years.

In a winner-takes-all shootout for the national top ranking, Stosur needed almost three hours to see off the 23-year-old to extend her record reign as Australia’s queen of the court to an incredible 451st consecutive week.

Crowning a banner day for Australian tennis on French Open eve, Ash Barty and Casey Dellacqua also landed the doubles title on Saturday with a 6-4 6-2 victory over top seeds Hao-Ching Chan and Yung-Jan Chan.

Underlining her credentials for a second Grand Slam crown, 33-year-old Stosur held her nerve in a roller-coaster encounter to secure her ninth WTA trophy – and second in Strasbourg after also hoisting the trophy as a wildcard in 2015.

While Gavrilova can console herself with a further rise to a new career-high No.24 in the world, Stosur will return to the cusp of the top 20 after also atoning for a three-set loss to Alicia Molik in the previously most recent all-Aussie WTA final in Sydney in 2005.

Both championship deciders lived up to their billing.

A 10-minute opening game offered an insight into what was to come on Saturday.

Stosur staved off four break points before finally succumbing and then also dropping her second service game to fall behind 3-1.

She broke back and conjured a 5-4 lead, only to falter twice more as Gavrilova pocketed the first set after an hour of ebbing and flowing.

Gavrilova stood within two games of victory at 4-4 in the second set, only for Stosur to nab the only break of the set to snatch it and draw level.

As in the first set, Stosur fell behind early in the third, but recovered to break straight back for 1-1 and then forge ahead to 5-2 when Gavrilova dropped serve for the third time in four games.

There was no coming back as Stosur sealed victory after two hours and 45 minutes, before expressing her relief at being able to serve out the high-stakes affair.

Congrats @BamBamSam30!

Lift that @WTA_Strasbourg 🏆 pic.twitter.com/f9peXQVy9H

— wta (@WTA) May 27, 2017

“Sometimes that’s not a easy thing to do, especially in a final, but I felt like I stayed really composed,” she said.

“I definitely was expecting a very tough match against Dasha. We know each other very well and we’ve practised a lot.

“She typically makes her opponents work very, very hard to make sure that they can beat her. That was exactly what I was expecting. I thought it could be very long and tiring and very physical.

“I just tried to hang in there. She was playing very well, especially at the start, and it was only the last few games in the third set that she started to make a few errors and I was ale to capitalise on that.”

It was Gavrilova’s second defeat in as many finals, having also lost in Moscow, her birth city, last October to former compatriot Svetlana Kuznetsova.

But the one-time world junior No.1 should nevertheless fancy her chances of a deep run in Paris after winning seven claycourt matches in the past fortnight in Rome and Strasbourg.

Seeded for the first time at the French Open, Gavrilova opens her campaign on Monday against Belgian Elise Merterns.

Stosur, seeded one spot above Gavrilova at No.23, also plays on Monday; the 2011 US Open champion will face Kristina Kucova of Slovakia.