Lleyton Hewitt could be set for a shock return after replacing Nick Kyrgios in Australia's Davis Cup team for their tie against the United States.
The 35-year-old retired after the Australian Open but may be set for an unexpected comeback in the World Group first-round tie.
Hewitt, the team captain, replaced Kyrgios - who has battled a virus and a back injury in the lead-up.
The big-serving Sam Groth has been promoted to play in both singles and the doubles on the grass at Kooyong.
Bernard Tomic is playing in the other singles rubbers, meaning Hewitt may yet just watch on.
This marks a first tie as captain for Hewitt, a two-time grand slam champion.
Groth will take on John Isner and Tomic faces Jack Sock on the opening day on Friday.