MELBOURNE, Australia (AP) Lleyton Hewitt called it quits on a 20-year career during the Australian Open in January. On Thursday, he was placed on standby as playing captain for Australia against the United States in the first round of World Group play at the Davis Cup.

So much for life in retirement.

Hewitt, 35, replaced a virus-struck Nick Kyrgios in the Australian team, although he wasn't included in the opening three matches. Hewitt took over as Australia captain at the start of this year, and when asked then if he would ever play Davis Cup again, said the chances were ''zero.''

But that changed with Kyrgios feeling under the weather and not available to play.

''We took him (Kyrgios) through his paces this morning and gave him a little fitness test to see how he pulled up from yesterday, but he just wasn't fit enough to play this weekend,'' Hewitt said. ''It's bad timing for us but it was really out of our hands and the end.''

The draw for the first-round tie on grass at Kooyong, the former home of the Australian Open, was held Thursday morning. Sam Groth will open Friday against John Isner in singles, with Bernard Tomic playing Jack Sock in the second match.

On Saturday, Groth and John Peers were scheduled to play doubles against Bob and Mike Bryan, although that lineup can be changed on the morning of the match, along with reverse singles on Sunday. There was speculation that Hewitt could replace Groth in doubles if Groth was tired from his singles match.

''We'll just see how it pans out,'' Hewitt said. ''We've got to put our best options forward every single day and we will have a look at it after each day's play and see how Sam plays and pulls up after his singles.''

U.S. captain Jim Courier said he wasn't surprised by the Australian team change.

''We've seen how much Lleyton was practicing this week, and with Nick's pretty conspicuous absence,'' Courier said. ''But it's certainly not something coming down here that we were anticipating.''

Kyrgios was affected by a virus while also struggling with a back injury which forced him to withdraw from his semifinal match in Dubai last week.

Hewitt is Australia's most successful Davis Cup player, having won 58 of the 78 singles and doubles matches he's played since his 1999 debut.

He helped lead Australia to its 1999 title and again in the winning final against Spain in 2003. He made his last appearance for Australia in its World Group semifinal loss to Britain last year.

Tomic has lost both his meetings with No.23-ranked Sock, but after reaching the final of an ATP tournament in Mexico last week, the Australian is feeling confident.

''I'm playing very well and I'm playing on a surface that's my favorite,'' Tomic said. ''I love this grass; it's not too quick and I move well on it so it suits my tennis. It's going to suit Grothy as well.''

Australia and the United States are meeting for the 46th time - but the first since the 1999 quarterfinals, when Australia went on to beat France for the title. The U.S. has a leading 32 Davis Cup victories, with Australia second with 28.