Ajla Tomljanovic is vowing to bounce back once more after suffering another untimely knee injury in Australia's Billie Jean King Cup quarter-final exit to Slovakia.

An inspired Viktoria Hruncakova defied her lowly ranking to defeat Kim Birrell in a tense three-setter before in-form Rebecca Sramkova sealed a 2-0 victory with a confident win over a crestfallen Tomljanovic.

Australia had been chasing a fourth semi-final appearance in five years, and a first title in half a century in the prestigious teams' event formerly known as Fed Cup.

Instead, Sam Stosur's first year as captain ended in disappointment at Malaga's Marten Carpena Arena as the Slovakian underdogs continued their dream week in Spain.

Stosur pulled somewhat of a selection surprise in calling up Birrell ahead of Olivia Gadecki for the opening singles rubber.

While both options had made maiden WTA Tour finals in recent times, Gadecki was higher-ranked after breaking into the world's top 100 for the first time following a charge to the Guadalajara Open title decider in September. Birrell, though, was also riding high after making last month's Japan Open final and entered Sunday night's match well-fancied to account for the 241st-ranked ranked Hruncakova.

Alas, the 26-year-old world No.115 went down 7-5 6-7 (4-7) 6-3 in a rollercoaster two-hour, 31-minute battle to pile the pressure on the resurgent Tomljanovic.

"Kim was very, very close to getting that first match our way, which was great. I thought it was a really good, quality match. That was unfortunate to be down 1-0," Stosur said.

Back as Australian No.1 after landing a second career title in Hong Kong following more than a year out with a knee injury, Tomljanovic's return to the competition ended in despair.

The 31-year-old needed a medical time-out in the first set for another left knee issue after falling awkwardly and never recovered, going down 6-1 6-2 in little more than an hour.

"It didn't feel good in the moment," Tomljanovic said.

"I don't really have much more info for you than that. Definitely felt really hard to get back on track after that because having a previous injury there, it never feels good to feel something go wrong.

"I mean, I always bounce back, so I will but it's definitely a tough day, especially when it almost feels like I would have taken this a bit easier if it was just a regular tournament for myself, but you don't want to let your teammates down.

"So it was a pretty bad ending to today."

Sramkova had upset world No.11 Danielle Collins, Ash Barty's 2022 Australian Open final foe, in Slovakia's shock win over the USA on Friday to make the quarter-finals.

Now the 28-year-old looms as pivotal to Slovakia's chances of continuing their giant-killing run against Great Britain in the semi-finals on Tuesday.

The Brits beat defending champions Canada 2-0, with Emma Raducanu and Katie Boulter scoring straight-set wins over Rebecca Marino and Leylah Fernandez.

Poland and Italy face off in Monday's first semi-final.