The withdrawal of Nick Kyrgios has not sapped captain Lleyton Hewitt's faith in a reshaped Davis Cup line-up in which he may yet play an active on-court role, despite naming Sam Groth for singles duty as well as the expected doubles partnership with debutant John Peers.

Kyrgios was ruled out of the first-round tie against the US on Thursday morning, having been debilitated by a virus he contracted last week in Dubai. Hewitt took his place in the four-man team but did not nominate himself for any of the five matches to be played over the next three days. That could still change, though, and well might.

"We'll just take it one match at a time and see how it all pans out," Hewitt said after a draw that will see Groth open against world No.11 John Isner, with Bernard Tomic to follow against US No.2 Jack Sock.

"There's five matches and we've got to win three of 'em, and that's the focus right now and we've got to put our best options forward every single day. And we'll have a look at it after each day's play and work out the best strategy for the following day. But at the moment I'm very confident going into tomorrow.