Davis Cup captain Lleyton Hewitt is on standby to play one more tie for Australia in this week’s clash against the United States at Kooyong, replacing Nick Kyrgios.

Hewitt was added to the team to replace Kyrgios, who has been battling illness and a back injury.

Sam Groth will replace Kyrgios in the singles and has been drawn to play John Isner first-up when the tie begins at Kooyong on Friday.

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Bernard Tomic will play Jack Sock in the other singles match before Groth and John Peers contest the doubles on Saturday.

Should Groth be too fatigued to back up for the doubles, which appears likely, Hewitt will step up for some more Davis Cup heroics while Groth is rested for the reverse singles.

Australia can make a change to its representatives up to an hour before play.

Hewitt, 35, has been at the forefront of Australia’s Davis Cup team since making his debut against the US as an 18-year-old in 1999.

He was part of the Australian team that won the Cup in 1999, beating France in the final. Hewitt was also part of the victorious team that triumphed over Spain in the 2003 final.

Hewitt has won 58 of the 78 singles and doubles matches he played for Australia in Davis Cup, and holds the record for most Cup ties and singles wins for Australia.

His appearance in the semi-final loss to Great Britain last year was meant to be his last as a player before taking over as team captain.

Kyrgios trained for the first time with the Australian team on Wednesday but struggled in the heat, hampered by a virus that forced him to withdraw from the semi-finals in Dubai last week.

Hewitt had been standing in for Kyrgios in practice during the week and Australia coach Jason Stoltenberg was impressed by Hewitt’s energy during the team sessions.

“He thought he was retired and he’s been hitting more than these guys,” Stoltenberg said after Wednesday’s training.

“It’s probably the first time that a captain has actually had to get out and prepare as if he may play.

“He’s a great team man and he’ll do whatever he needs to do – whether that’s playing or sitting on the side.”