Shane Watson and Phil Hughes, uncertain of their positions leading into the series, have hit their straps in the practice matches.
In addition, Chris Rogers, Brad Haddin, Ed Cowan, Steve Smith and Usman Khawaja have all managed a half century each.
Australia are well on track to finish off Worcestershire on the final day, holding a 393-run lead at stumps on day three.
Worcestershire are 1-64 from 21 overs in their second innings, after the Australians set them a 457-run target following a second declaration at 5-344.
Hughes cemented a place in the line-up with a thrashing 86 on Thursday but it's anyone's guess where he'll end up in the order.
Clarke backed up his first innings 62 with a brilliant 124.
The ton was brought up in 90 balls with 13 fours and two sixes.
It was a powerful message from the skipper that he's put his back trouble to bed for the time being and is ready to lead in his fifth Ashes series.
Cowan's performance against Worcester was most ambiguous.
He scored 58 and 34, but looked unconvincing for the most part.
In his first innings he slowed the scoring to a standstill and was involved in two unfortunate run outs. In his second bat he was dropped at first slip when on nought.
Since his maiden Test century in Brisbane last year, Cowan has made a habit of not being able to go on to big scores.
However, the left-hander hinted in a radio interview he'll bat at No.3 in the first Test.
"With Chris Rogers coming into the squad they were always eyeing off that number three spot for me, so it was good to get some runs hopefully to nail that down. Things are still looking pretty positive for me in terms of playing that first Test," Cowan told Sky Sports Radio, before his second innings.
Hughes was under as much pressure as anyone heading into the series, after struggles in India, an underwhelming lead-in and the fact he's been dominated by England in his previous five Ashes Tests.
But the left-hander was at his swashbuckling best at New Road, his former county home ground, smashing 13 fours and three sixes in his 84-ball knock.
At one point Hughes enjoyed seven fours and a six in just 11 balls.
He was ultimately bowled attempting an audacious flick down the leg-side.
Steve Smith made 43 to go with his 68 in the first innings.