Alex Doolan, Shaun Marsh and James Faulkner are locked in a three-way battle for the Test berth vacated by George Bailey as selectors contemplate a reshuffle of the batting line-up for the series against South Africa.

Despite making what John Inverarity said was a "very significant" contribution to Australia's Ashes whitewash, selectors chose not to back Bailey against the high-class pace attack of Dale Steyn, Vernon Philander and Morne Morkel.

They gave the nod to Marsh and the uncapped Doolan for his first Test tour in a move that also highlighted the thin batting depth in Australian cricket. Phillip Hughes was overlooked, despite excellent form in the Sheffield Shield for South Australia. The trio, along with Bailey, had been in contention for the final two batting berths on the tour, Inverarity said.

There could be more changes to come in South Africa after Inverarity foreshadowed the possible movement of Shane Watson from first drop to No.6 so the all-rounder could bowl more.

That would leave Doolan and Marsh in a possible head-to-head contest for the No.3 berth in Australia's tour game against a South African Invitational XI in Potchefstroom starting on February 5.

Selectors could also opt for a like-for-like swap for Bailey, in which case Watson would remain at No.3, and Doolan and Marsh fighting for the vacated No.6 slot.

"It could be the batting order is rearranged. No.6 is a real option, but with Shane Watson we're very keen for him to do plenty of bowling," Inverarity said.

"Michael Clarke and Darren [Lehmann] may consider he drops down the list but that's yet to be decided. That's always been an option; nothing's changed there."

All-rounder Faulkner, whose batting has impressed in the ODI arena, could come into the mix if selectors decide to bolster the bowling against the Proteas' strong batting.

In this scenario, Faulkner would likely bat at No.7 and the in-form Brad Haddin move up a position.

While Bailey averaged only 26 in the Ashes, the men in line to replace him, Marsh and Doolan, have only posted moderate, rather than stellar, numbers at Shield level. Marsh is in line for a Test recall after what Inverarity said at the time was a "traumatic" series against India, in which he scored a paltry 17 runs from six innings. Inverarity believes he is now in a better frame of mind.

His 44 in the first innings of the dramatic Cape Town Test of 2011 was also noted by Inverarity.

Selectors have shown massive faith in the gifted left-hander, who averages a moderate 35 from 85 games in a first-class career spanning 14 seasons. At Test level, the 30-year averages 27 after seven appearances.

"He's in a good place, Shaun. He's playing well, and we all know when Shaun plays at his best he's a very good player. And it seems to us as though he's in that space at the moment, so we're hoping he'll do really well," Inverarity said.

Doolan, 28, is on the verge of a Test debut despite passing 50 only once in nine firast-class innings since crunching a century against NSW in November. However, he is highly rated by selectors, who are prepared to look beyond an underwhelming first-class average of 38.

"Those of us who have seen him play, when he plays he looks a very good player – good technique, time, plays pace bowling well – so we're hoping he'll really flourish in this environment," Inverarity said.

Inverarity said the door had not been closed on George Bailey. "It's the same with any players; they've all got to do their best, and what we as a selection panel want is lots of competition for players. Players performing and doing really well . . . really pushing for claims," he said.

James Pattinson and Jackson Bird pipped Nathan Coulter-Nile in the pace-bowling ranks but Inverarity said the incumbent trio of Mitchell Johnson, Ryan Harris and Peter Siddle would likely play the first Test.

Australian squad for tour of South Africa: David Warner, Chris Rogers, Shane Watson, Michael Clarke (c), Steve Smith, Shaun Marsh, Alex Doolan, Brad Haddin (vc), Mitchell Johnson, Ryan Harris, Peter Siddle, Nathan Lyon, James Faulkner, Jackson Bird, James Pattinson.