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With the score 1-1, victory on Saturday would mean Andy Murray could win the best-of-five tie for Great Britain in Sunday's first reverse singles.
Jamie Murray and Dom Inglot were originally named to face Lleyton Hewitt and Sam Groth.
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But captain Leon Smith exercised his right to change the line-up.
"Everyone in the team wants to play, everyone wants to try and help where they can," Andy Murray said on Friday.
Jamie Murray has reached the last two Grand Slam finals, at Wimbledon and the US Open, with Australian partner John Peers, while Inglot reached the semi-finals in New York with Sweden's Robert Lindstedt.
Britain captain Leon Smith had said he would not decide on his line-up until after Friday's play, saying he needed to "talk to Andy", but he has now opted for the pairing who secured a four-set victory over Nicolas Mahut and Jo-Wilfried Tsonga in the quarter-final against France.
Murray, the world number three, thrashed Thanasi Kokkinakis 6-3 6-0 6-3 in Friday's first singles match against Australia, before Bernard Tomic beat Dan Evans 6-3 7-6 (7-2) 6-7 (5-7) 6-4.
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Australia captain Wally Masur admitted his side were feeling the pressure ahead of the crucial third rubber.
"The locker room is pretty tense because I guess we thought it would be 1-1 and it's come to that situation, where there's so much focus on the doubles," he said.
"Everybody knows how pivotal that match will be but we're very happy to be in it."

The number of people claiming unemployment-related benefits now stands at 43,500.
It reverses June's increase in the number of jobless - which had been the first jump in 28 months.
However, Northern Ireland's unemployment rate of 6.5%, remains above the UK average.
The figures also show that long-term unemployment continues to be a problem in Northern Ireland.
Northern Ireland's rate of 59% is well above the UK average of 31%, while youth unemployment is also higher.
Enterprise Minister Jonathan Bell welcomed the fall in unemployment claimants, but said the levels are back to where they were a year ago.
"The latest figures reiterate the continued challenges faced by the Northern Ireland labour market and the impact of continued uncertainty in global markets," he said.
"The Northern Ireland unemployment rate [6.5%] is above that for the UK [5.6%], however, it continues to compare favourably to the April 2015 rates for the European Union [9.6%] and the Republic of Ireland [9.8%].
"In the face of these challenges it is important local businesses continue to seek new foreign investment and export opportunities."

Harry Dunn worked for clubs including Chelsea, Liverpool and Rangers.
Police said an 84-year-old man was arrested and charged with a number of "non-recent sexual offences".
Last year, Police Scotland was among forces across the UK to launch investigations into allegations of child abuse within football after reports from high-profile players.
Mr Dunn is understood to have worked with Liverpool and Rangers in the 1980s and later with Chelsea.
It is thought he now lives in Edinburgh.
Andy Murray will team up with his brother Jamie for Saturday's crucial doubles match against Australia in the Davis Cup semi-final.
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Unemployment in Northern Ireland fell by 400 in July, according to the latest government figures.
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A former youth football scout has been arrested by police investigating allegations of historical sex abuse.