The intrigue around the final make-up of Australia’s Davis Cup lineup deepened at Kooyong on Wednesday with the door left ajar for Lleyton Hewitt to make a shock return to the court against the United States.

Nick Kyrgios finally arrived in Melbourne after battling a mystery virus, with Sam Groth placed on standby should the world No.27 fail to shake the bug.

But team captain Hewitt has been a constant presence on the practice courts at Kooyong in the lead-in to the first-round tie, sparking conjecture he could be set to make a surprise comeback just weeks after retiring.

“I don’t know actually – he’s enjoyed the hitting though – he thought he was retired and he’s been hitting more than these guys,” team coach Jason Stoltenberg said of the prospect.

“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. We don’t expect that he’ll play but we’ll have to wait and see over the next 24 hours.

“But he’s been hitting a lot of balls. He’s a thinker, he thinks ahead and he’s pretty organised. I’d say that in his mind he’s just covering all of his bases.”

Stoltenberg confirmed Kyrgios would hit with his teammates on the Kooyong grass on Wednesday afternoon.

Groth – who will partner John Peers in Saturday’s doubles rubber – says he is ready to step in should either Kyrgios (back/hip/virus) or Bernard Tomic (wrist) be forced to pull out of Friday’s opening singles matches.