Ashleigh Barty defeated America’s Madison Keys in straight sets to put Australia up 2-1 on Monday morning in the world group first round clash in Asheville, North Carolina.

Australia needs just one victory in the remaining two rubbers later Monday for an upset win over the US and move into the semi-finals against Belarus in April.

Barty overcame a shaky start to steamroll Keys 6-4 6-1.

The world No.13 lost her first two service games to trail 0-3 in the first set, but was able to grind her way back and dominate 17th ranked Keys.

Australia and the US have shaken up their line-ups for the final singles rubber.

Queensland’s Kimberly Birrell was scheduled to play Sofia Kenin, but after both lost their opening singles matches on Saturday it will be Australia’s Daria Gavrilova against Danielle Collins.

If Gavrilova loses, the tie will be decided in the final doubles rubber.

Ahead of Monday’s match, Barty said she was not feeling any pressure and was happy to carry the load in the aptly named Asheville.

“No pressure at all,” she said after her opening singles rubber 6-1 7-6 (7-2) against US No.2 Sofia Kenin.

“For me it is an opportunity to go out there and play for my country and enjoy the fact I have the privilege of putting on the green and gold and wearing Australia on my back,” Barty said.

🇦🇺 1-1 🇺🇸
Everything to play for tomorrow! 💛💚 @FedCup pic.twitter.com/O5ml6PXceh

— Ash Barty (@ashbarty) February 9, 2019

Australia made it back to the world group for the first time since 2015 after battling its way through qualifying rounds.

“I’ll put everything I possibly can on the line for my country, my captain and team,” Barty said before the tie began.

Keys, who is ranked 17th in the world, later evened the score with a convincing 6-2 6-2 win over Birrell.

Birrell, who made the third round of the Australian Open in January and rose to No.157 in the world, was selected by team captain Alicia Molik ahead of No.47 Daria Gavrilova.

But her inexperience showed as she was outclassed by the heavy-hitting Keys.

“I did the best I could, but the weight behind her shot was definitely different to anything I have really felt before,” Birrell said.

The power of Madison Keys was too much for Kimberly Birrell. Photo: Getty Images

Fresh off her run to the Australian Open quarter-finals, Barty will partner Gavrilova against American duo Nicole Melichar and Danielle Collins in what could be the deciding doubles rubber in the five-match format.

Britain’s Johanna Konta is consoled by coaching staff after winning at the University of Bath. Photo: Getty

Elsewhere, Johanna Konta collapsed on court but recovered to lead Britain to victory over Serbia, while France is in command against Belgium.

Konta, 27, needed to steady herself on her chair before falling to her hands and knees on her way off court, where she was helped by volunteers and paramedics midway through her match with Serbia’s Aleksandra Krunic.

But the British No.1 returned seven minutes later after a medical assessment to earn a 7-6 (7-1) 3-6 6-2 win, which sealed a 2-0 success in the best-of-three tie.

“I started progressively feeling more and more unwell,” Konta said.

“Light-headed, feeling shaky, feeling a little bit out of body. It got the better of me at the end of the second set. I tried not to panic and tried again to assess what I could and do the best I could.

“I was going to go as far as I could.”

Katie Boulter earlier gave Britain the lead, beating Ivana Torovic 6-4 6-4.

At Ostrava, Romania and the Czech Republic are tied 1-1.

Australian Open semi-finalist Karolina Pliskova gave the home team a flying start as she eased past Mihaela Buzarnescu 6-1 6-4, before Romania’s Simona Halep routed Katerina Siniakova 6-4 6-0.

Clear your schedules.

In #FedCup action later: @KaPliskova v @Simona_Halep 😍 pic.twitter.com/YrGsC2zc8U

— Billie Jean King Cup (@BJKCup) February 10, 2019

The game between the former world No.1 players could be decisive.

At Liege, Caroline Garcia returned to the Fed Cup for the first time since the 2016 final to overcome Alison Van Uytvanck 7-6 (7-2) 4-6 6-2 and give France the first point against Belgium.

Alize Cornet made it 2-0 after defeating Elise Mertens 7-6 (8-6) 6-2.

-with AAP