Australia has roared into the ATP Cup semi-finals with a rollicking doubles win from shock first-time pairing Alex de Minaur and Nick Kyrgios.

Key points: Kyrgios and de Minaur were a daring selection gamble from captain Lleyton Hewitt

Kyrgios and de Minaur were a daring selection gamble from captain Lleyton Hewitt De Minaur was backing up from losing in the singles

De Minaur was backing up from losing in the singles Barty lost to American qualifier Jennifer Brady in Brisbane

In a daring selection gamble, Australian captain Lleyton Hewitt replaced doubles specialists John Peers and Chris Guccione with his two singles spearheads after an inspired Dan Evans levelled the tie for Great Britain with an epic victory over de Minaur.

But a lion-hearted de Minaur rebounded from his three-hour, 22-minute singles loss to pull off a rousing 3-6, 6-3, 18/16 triumph with Kyrgios over two-time grand slam doubles champions Jamie Murray and Joe Salisbury.

The thrilling triumph, after saving four match points in the super-tiebreak, almost raised the roof at the new-look Ken Rosewall Arena and fired Australia into a semi-final showdown on Saturday night with Rafael Nadal's Spanish Davis Cup champions or Canada.

Staring down their fourth match point, de Minaur and Kyrgios each rifled spectacular backhand return winners before Kyrgios closed out the contest with an unreturnable serve.

A jubilant Kyrgios carried de Minaur off court to celebrate with the Australia's courtside box.

Nick Kyrgios and Alex De Minaur were a surprise pairing for the doubles. ( AAP: Mark Evans )

Revelling in the team environment, Kyrgios had given Australia a flying start with an emphatic 6-2, 6-2 win over Cameron Norrie in Thursday's opening match before Evans denied de Minaur 7-6(7/4), 4-6, 7-6(7/2) in the match of the tournament.

But few could have predicted the drama to follow with de Minaur and Kyrgios never having paired up before.

Despite their proven singles prowess, neither are doubles mugs.

De Minaur played 11 doubles tournaments last year.

He partnered Peers to knock off Jack Sock and Leander Paes, both multiple grand slam doubles champions, as well as the top-ranked pairing of Robert Farah and Juan Sebastian Cabal to make the semi-finals in Washington.

Kyrgios also contested 11 doubles events in 2019, his most notable win a victory with Sock over Rafael Nadal and Stefanos Tsitsipas.

But Thursday's win was another level, given the high stakes and massive $22 million prize money on offer at the inaugural ATP Cup.

Russia will face Argentina in Thursday night's second quarter-final.

Spain and Belgium clash on Friday night, after the Novak Djokovic-led Serbia take on Canada in that day's first quarter-final.

Barty off to shaky start in 2020

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 20 seconds 1 m 20 s Barty couldn't catch up to Jennifer Brady at the Brisbane International

Meanwhile, Ash Barty's 2020 season is off to a shaky start after she lost her opening singles match of the year at the Brisbane International in straight sets to American qualifier Jennifer Brady, 6-4, 7-6 (7/4).

World number one Barty was uncharacteristically sloppy, hitting 26 unforced errors to her opponent's 15, as she worked through her off-season rustiness against an opponent who was already playing her fifth game this week.

Barty pledged to donate her winnings from the Brisbane International singles and doubles competitions to the Australian Red Cross appeal.

In losing at the second round stage of the singles, Barty will claim $32,000 for the appeal, and could add up to $61,000 more should she claim the doubles prize.

"You can call it rust or you can just call it a bit of execution," Barty said.

"For me it was on those returning games. I had probably had half a dozen second serve returns where I failed to make it into the court, in that first set in particular.

"And then Jen grew in confidence.

"You have to give credit where credit's due.

"But also for me that's probably the only point of the match where I look at and I'm a little bit disappointed in myself and a little bit disappointed with the execution."

Barty could not get near Brady's serve, failing to earn a break point, with the American taking the chance she had in the first set.

The crowd came alive as Barty rallied during the second set tie-break, but could not lift their home-town hero as she lost after 91 minutes of game time.

In front of a healthy and expectant crowd on Pat Rafter Arena — the first time the main show court at the Brisbane Tennis Centre had been used for the WTA Brisbane International after the ATP Cup controversially had priority at the start of the week — Barty was beaten by the superior power of an American opponent she had not lost to in two prior meetings.

The opening game of the match was simplicity itself for Barty, but as the first set continued, it became apparent that Brady would not just lie down and play the role of the sacrificial lamb for the massed supporters on Barty's home court.

Brady has already come through three games of qualifying on consecutive days and followed that by dispatching former world number one Maria Sharapova in a come-from-behind three-set victory on Tuesday.

That tenacity and grit was clearly in evidence against Barty, as the 24-year-old world number 53 played the better tennis throughout the match.

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In the first set, the American broke Barty after a bruising seventh game in which it was she, not the world number one, who was dominating the court.

Barty showed some delightful flashes throughout, but there was rust in there as well as the Australian hit 11 unforced errors in the first set, too often finding the net with her ground strokes.

It was a problem that plagued her as early as the warm-up, but was far from her only issue.

Brady's crushing ground strokes forced Barty further and further back behind the baseline as the American dictated terms during the lengthier rallies.

The expectation around Barty's home court was palpable, as every shot that hit the net was followed by an anguished groan of disappointment.

Barty still has the semi-finals of the doubles tournament to look forward to in Brisbane, with Dutch partner Kiki Bertens.

AAP/ABC