Alex de Minaur and Nick Kyrgios combined to edge Britsh pair Jamie Murray and Joe Salisbury on their fifth match point in the deciding doubles to give Australia a 2-1 win and a place in the ATP Cup semifinals.
Australia captain Lleyton Hewitt gambled on sending his two singles players back out for the doubles against the established British team and it paid off after a seesawing 3-6, 6-3, 18-16 victory, sealed in a gripping match tiebreaker.
Kyrgios gave Australia the lead with a 6-2, 6-2 win over Cam Norrie in the opening singles.
But De Minaur lost his 3-hour, 23-minute singles encounter to Dan Evans 7-6 (4), 4-6, 7-6 (2), after saving four match points, to send the first of the quarterfinals in the new international team competition to the doubles.
It was his first loss of the year, and he wanted to make amends immediately. Hewitt gave him the chance, pairing de Minaur with Nick Kyrgios instead of Chris Guccione and John Peers, who were unbeaten in three matches in the group stage.
The Australians will play the winner of Friday's quarterfinal between Rafael Nadal's Spain and Belgium.
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Australia didn't lose a match in the group stage as it finished with three 3-0 sweeps in Group F in Brisbane, securing its spot in the playoffs in Sydney with a match to spare.
Britain finished atop Group C with a 2-1 record in Sydney.
Russia was playing Argentina later Thursday in the second of the quarterfinals.