BRISBANE, Australia — Late substitute Jack Sock and partner Steve Johnson kept the United States alive in its Davis Cup quarterfinal with Australia, beating Sam Groth and John Peers 3-6, 6-3, 6-2, 2-6, 6-3 in Saturday's doubles.

The win on a hard court at Brisbane's Pat Rafter Arena reduced Australia's advantage to 2-1 ahead of Sunday's reverse singles.

U.S. captain Jim Courier replaced scheduled doubles player Sam Querrey with Sock about an hour ahead of Saturday's match, despite Sock having lost his singles match to Jordan Thompson on Friday.

After losing the opening set Saturday, the American pair steadily gained confidence throughout the match, defending strongly and forcing Australia to stay in long rallies.

In the fifth set, the Americans broke Peers' serve to love and outplayed the Australians to clinch the match.

On Friday in singles, Nick Kyrgios finished off John Isner with his 20th ace, beating the American 7-5, 7-6 (5), 7-6 (5) after Thompson upset Sock 6-3, 3-6, 7-6 (4), 6-4 to give the hosts a 2-0 lead.

On Sunday, Kyrgios is up first and scheduled to play Sock, and then Thompson is set to take on Isner.

"I'm super proud of these guys today, but it still will take a monstrous effort from us on Day 3," Courier said.

Johnson added: "There's no bigger honour than playing for your country. We weren't going to go down without a fight."

The winner of the quarterfinal will play Italy or Belgium in September. Belgium leads their quarterfinal 2-0 at home on an indoor hard court in Charleroi.

The U.S. has won the title a leading 32 times, with Australia second with 28. But the U.S hasn't won the Davis Cup since 2007, and Australia not since 2003.

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