Teenager Mika Stojsavljevic and Harriet Dart put a depleted Great Britain one win away from sealing a spot in the Billie Jean King Cup Finals over Australia in Melbourne.
Stojsavljevic, currently ranked 275th in the world, stunned world No 65 Talia Gibson 7-6 (7-4) 7-5 on her Billie Jean King Cup debut in Melbourne.
The 17-year-old was a 7-6 (7-4) 7-5 winner as she overturned a difference of 219 places in the WTA rankings.
The 2024 US Open junior champion gave Great Britain a perfect start in the qualifiers as Anne Keothavong's side look to progress in the absence of Emma Raducanu, Sonay Kartal, Katie Boulter and Fran Jones.
Stojsavljevic went 3-1 ahead early on but needed a tie-break to take the opening set and successfully defended five break points before closing out a see-saw second which included five breaks of serve.
"It feels amazing. I can't believe it. I can't even remember the last point," Stojsavljevic said. "I had amazing support from the side and managed to get through.
"Going into it, I knew she'd have the home ground. I'm grateful to the people supporting GB today.
"It was a good match. We have very similar games, both quite aggressive, so I'm happy I got through it."
Harriet Dart then battled back to defeat Kiimberly Birrell 4-6 6-3 6-3 to leave them requiring one win from the remaining three matches to qualify for the finals in Shenzhen, China from September 22-27.
"I'm super happy to be able to get the win after Mika's incredible performance earlier," Dart said.
"I'm very happy to notch the win - there were so many ups and downs throughout the match but in the end I was able to find the way.
"It's such a privilege to play for my country and I always enjoy it as much as I can and it's so nice to be able to get another win on the board."
Dart will look to complete the tie for Britain when she teams up with Jodie Burrage in Saturday's doubles rubber against Storm Hunter and Ellen Perez.
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