The United States have pulled a Davis Cup surprise, summoning Jack Sock for their must-win doubles rubber on Saturday against Australia in Brisbane.

Sock replaces Sam Querrey and will team up with Steve Johnson against Australian pair Sam Groth and John Peers at Pat Rafter Arena.

Australia lead the World Group quarter-final tie 2-0 after Sock’s defeat to Jordan Thompson and Nick Kyrgios’ classy win against John Isner on Friday, and will secure a semi-final berth in September against either Italy or Belgium with one more victory.