Strasbourg, France, 26 May 2017 | Darren Walton, AAP

Daria Gavrilova and Sam Stosur are on track to meet in a rare all-Australian WTA final after advancing to the last four of the claycourt event in Strasbourg.

Continuing their promising Roland Garros build-ups, Stosur hammered nine aces en route to a 7-6(5) 6-4 victory over Carla Suarez Navarro before Gavrilova denied fellow Australian Ashleigh Barty 6-4 6-7(3) 7-6(5) in a two-and-three-quarter-hour quarterfinal thriller on Thursday.

Aussie No.1 on the line @WTA_Strasbourg: Daria Gavrilova will be the new Aussie No.1, snapping Sam Stosur’s 450wk streak, if she wins title.

— WTA Insider (@WTA_insider) May 25, 2017

Along with Barty, Stosur and Gavrilova were the first Australian trio to make the quarterfinals of the same WTA event in 27 years.

Now the pair – separated by just one spot in the rankings – are the first Aussie women to reach the semis of the same event since Jelena Dokic and Jarmila Gajdisova in Kuala Lumpar, in 2011.

> Stosur: “What’s not to be happy about?”

But while Stosur preserved her record of not dropping a set all week, Barty pushed Gavrilova all the way in a rollercoaster encounter featuring a dozen service breaks.

.@Daria_Gav secures a spot in @WTA_Strasbourg Semifinals!

Beats Barty 6-4, 6-7(3), 7-6(5)! #IS17 pic.twitter.com/v8Dpl0Vyks

— WTA (@WTA) May 25, 2017

Barty raced out to a 3-0 lead only for Gavrilova to eventually reel her in; the Melburnian won six of the next seven games to pocket the first set.

Backing up her impressive run to the quarters last week in Rome, Gavrilova led 4-2 in the third set only for Barty – the resurgent former Wimbledon junior champion – to roar back to take the match to a deciding tiebreaker.

Barty once again rallied from a mini-break down at 2-5 before Gavrilova finally clinched victory with an unreturnable serve to secure her sixth win from her past seven matches on the red dirt.

“It’s really cool,” Gavrilova said.

“I’m really excited. It couldn’t get any closer. I knew it was going to be a tough battle. She’s such a great player.

“It was tough mentally. We were both fighting really, really hard to win.”

The last time two Australians clashed in a final came in Sydney in 2005, when Alicia Molik beat Stosur 6-7(5) 6-4 7-5.

A Strasbourg champion in 2015, sixth-seeded Stosur will play China’s Peng Shaui on Friday for a place in Saturday’s final, while Gavrilova will face Frenchwoman Caroline Garcia after the defending champion got past Kristyna Pliskova.

Barty, meanwhile, is still alive in the Strasbourg doubles event; she and another Aussies, Casey Dellacqua, will face either Taiwanese top seeds Hao-Ching and Yung-Jan Chan, or qualifiers Chantal Skamlova and Eva Wacanno.