AMERICAN Jack Sock has redeemed himself to take the Davis Cup quarter-final against Australia into a deciding day after making good in his late substitution into the doubles.
Sock was penetrative as any player on court in the fifth set after he was drafted into the doubles with Steve Johnson and reduced Australia's lead in the tie to 2-1 at Pat Rafter Arena.
They edged out Australians John Peers, ranked third in the world in doubles, and Sam Groth 3-6, 6-3, 6-2, 2-6, 6-3.
American captain Jim Courier said on Friday night that the US team would "rally" around Sock, a former Wimbledon doubles champion, after he had finished with energy tanks near empty in a four-set loss to the lower-ranked Jordan Thompson.
A singles win on Sunday by either Nick Kyrgios or Thompson would give Australia a place in the semi-finals, on September 15-17, for only the second time since 2006.
Sock, who has played 5hr 34min of tennis in two days, is scheduled to play Kyrgios first-up, with John Isner to take on Thompson in the fifth and final match.
Sock declined to say at his press conference after his loss to Thompson why he had played with such fatigue, but later on Friday told the Davis Cup website he was struggling with a cold.
"I've got a head cold right now and trying to fight through it - not feeling great. My game is feeling good," Sock said.
The Americans hit three winners in Peers's service game when they gained the vital break in the fifth set at 2-2.
The Americans can change on Sunday morning their nominated singles players and Sam Querrey has a last-start win to his credit over Kyrgios, last month in Mexico.
"It's fun to have a breather and have something to play for tomorrow," Courier said.
After an uncertain start to the doubles, less than 24 hours after his fading four-set singles loss, Sock played with more energy and precision.
Late in the first set of the doubles, former Australian Davis Cup winner Todd Woodbridge said on Channel Seven commentary that Sock looked as "flat as he was when he finished the match" on Friday.
Sock's service game at 1-2 was the only game in the first set to go against the server, but two missed volleys from Johnson in it contributed.
Groth's service was the one to be broken in the second set to level the match and both Australians lost service games to drop behind 0-4 in the third set.
Sock served out the third set 6-2 with growing confidence and both Americans left the court for a break.
Johnson was shaky in his service game at 2-3, which the Australians won with a forehand return winner by Groth, and Sock was broken to tie the match up at two sets each when Peers produced consecutive winners.
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