After a year-long farewell tour of the tennis circuit, Lleyton Hewitt finally said goodbye in January at the Australian Open. But his ‘retirement’ as a player may be short-lived.

The 35-year-old new Davis Cup captain looks likely to play in the tie against the United States which begins tomorrow.

His return to playing has been forced on him by the withdrawal from the tie of Nick Kyrgios, who has been struck down by a mystery virus.

As Davis Cup captain Hewitt is essentially responsible for picking who plays and when and creating a team environment in a very individual sport. Traditionally they watch from the sidelines and coach at changes of ends.

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To actually play in ties is not part of the job description.

But that is set to change, after Hewitt was named in Australia’s squad for the World Group first round clash against the United States, which starts at Kooyong on Friday.

Thursday’s draw announcement said Sam Groth would play John Isner in the opening singles tomorrow, then doubles on Saturday with John Peers against the Bryan brothers, and singles again on Sunday against Jack Sock. That would leave Hewitt without a match. (Bernard Tomic will play Sock in the second singles match Friday and Isner on Sunday.)

Those line-ups are subject to change – Hewitt appears set to play doubles with Peers on Saturday, giving Groth a day of rest.

Kyrgios battled through practice on Wednesday. Photo: Getty

Both Kyrgios and Tomic have been in good form recently: the former won his first ATP title in Marseille and Tomic reached a final in Acapulco.

Kyrgios also met Stanislas Wawrinka – for the first time since he uttered that infamous sledge – last week in the semi-finals of the Dubai Tennis Championships.

But the Aussie was forced to retire with a back problem, putting in doubt his involvement in this week’s tie, as he also battled sickness.

Hewitt hasn’t played since bowing out of the Australian Open more than a month ago after losing in the second round of the singles and the third round of the doubles in which he was paired with Groth.

Kyrgios’ mystery illness – so unknown that even Australia’s coaching staff admitted they were unsure of what it is – saw him miss his team’s first two practice sessions, media duties and the official team dinner.

And his battle through a practice session on Wednesday did not convince anyone that he is fit to play.

His mother Noralia described the illness as a “terrible virus“, while Aussie coach Jason Stoltenberg conceded his wellbeing was still a problem.

Stoltenberg also said Hewitt was practicing for hours in the build-up to the tie.

“He thought he was retired and he’s hitting more than these guys [players]. It’s probably the first time a captain’s had to get out and prepare as if he may play,” he said.

“He’s a great team man and he’ll do whatever he needs to do.”

Groth added: “I don’t think you see many captains hitting as many balls as him, but I think he actually enjoys being a part of that as well.

“The guy got to No.1 in the world and won Wimbledon – he can definitely hit a ball on a grass court.”

Groth will replace Kyrgios in the singles. Photo: Getty

Hewitt’s comeback appeared so likely that the Americans were even preparing to face him.

“We won’t be surprised [if he plays],” doubles legend Bob Bryan said.

“I mean, Lleyton’s put in a lot of work this week. Our practice courts are right next to theirs and he’s been playing a lot of singles, been playing doubles, so we’re gonna be ready for anything.

“The guy’s a legend and he’ll step up just fine.”

Hewitt was world No.1 and won grand slams at Wimbledon and the US Open, but he’ll be most fondly remembered in Australia for his Davis Cup heroics.

He deserved better than to say goodbye so early in this year’s Australian Open.

The South Australian is arguably Australia’s greatest Davis Cup player – and this is the stage he should go out on.

When Kyrgios last entered a Davis Cup tie not at 100 per cent, it all went pear-shaped against Kazakhstan in Darwin.

Confirmation of the change; Hewitt in and Kyrgios out; came on Thursday morning (AEST).