Bresnan poser for England
England's selectors will already know the nucleus of the squad which will bid to make history this winter as they eye another Ashes series win.
The bankers and match-winners who have largely been part of the last three in succession will all be named on Monday.
If that accounts for all but one of the first-choice XI, though, it is the identity of the remaining six which will make for lengthy deliberation this weekend.
Among the extra half-dozen, the obvious plan is to try to cover all eventualities and at any rate have cricketers who can collectively deputise for any injury or add strength to any department.
One immediate complication is the fitness, or otherwise, of Tim Bresnan - who missed the final Test at the Kia Oval, and then the NatWest Series, because of a stress fracture in his back.
Bresnan is twice an Ashes winner already, and occupies a pivotal position as England's third seamer and an ever-improving number eight.
He has twice significantly scarred Australia, with his precious runs and then the crucial wicket of David Warner in last month's series-clinching win in Durham, and before then 11 victims in the final two Tests of England's 2010/11 victories at Melbourne and Sydney.
England will be loth to leave him behind, and are expected to name a squad of 17 with extra cover for Bresnan.
The contenders account for one of four intriguing discussions.
The others, of course, are second spinner, wicketkeeping cover for Matt Prior and - linked with the latter - who will bat at number six.
Like Bresnan, Chris Tremlett's 2010/11 intervention - after replacing the out-off-form Steven Finn at Perth - remains a lasting image of England's supremacy.
That will count for much in his favour, as will bowling coach David Saker's predilection for tall fast bowlers.
Against Tremlett, however, is the sense that - despite a career-best eight for 96 against subsequent county champions Durham last month, and his previous selection in the squad for the Oval - he has perhaps not quite done enough to convince he is the same bowler since his Test career was last interrupted by physical frailty 20 months ago.
All fast bowlers, of course, are hostages to fortune with injury - and Tremlett's most obvious rivals Finn and Boyd Rankin are no different.
With doubts sure to persist over Bresnan, however, a marginal decision may fall in favour of Finn and Rankin as another third-seamer option ahead of Tremlett and Graham Onions.
The like-for-like equation as specific cover for Bresnan's skills appears to concern Oval debutant Chris Woakes and coming force Ben Stokes.
Even allowing for England's insurance policy of a Performance Programme squad to shadow the tour during the first two Tests, there could be room for Woakes and Stokes in the 17.
Both are potentially genuine all-rounders - which means they could also enter calculations to balance the team from number six.
Woakes replaced Jonny Bairstow there at the Oval, and acquitted himself well with the bat.
England will be reluctant to dispense, even temporarily, with Bairstow - also the most obvious wicketkeeping deputy - after investing 12 Tests in him.
He may nonetheless be vulnerable to the combined case for Stokes and Woakes, as well as Jos Buttler behind and in front of the stumps, and in the week of his 24th birthday there may be disappointment for the Yorkshireman.
Two more awkward puzzles remain to be solved.
England must nominate a second-spinner contingency for Graeme Swann.
Convention, and therefore instinct, often dictates selectors opt for variety here.
But it is hard to see them needing two spinners in the same XI, even in Sydney, so the policy should be to identify the best off-spin understudy rather than a complementary slow left-armer.
In any case, doubts over Monty Panesar's behaviour off the field and worries about Simon Kerrigan on it - after his hapless debut at the Oval - leave the cupboard light, if not exactly bare, when it comes to left-arm spin.
Leg-spinner Scott Borthwick has made strides this summer, more so with bat than ball, for champions Durham - yet despite his three limited-overs caps, he appears too left-field for Andy Flower's regime, especially with the Kerrigan experiment still so raw.
By a process of elimination therefore, James Tredwell - the only off-spinner apart from Swann on England's recent radar - is left, even after his NatWest Series travails.
When all of the above is settled, and depending to an extent on how, comes perhaps the trickiest call of all - the extra batsman.
England need not just someone who can populate the middle order but deal with the new ball.
Injury, or a malfunction for the still inexperienced Joe Root, dictates that.
Nick Compton remains the batsman who fits the bill, but the thorny question is whether England's management have it in them to recall him.
Possible England Ashes squad: AN Cook (Captain), JE Root, IJL Trott, KP Pietersen, IR Bell, BA Stokes, MJ Prior (wkt), TT Bresnan, SCJ Broad, GP Swann, JM Anderson, JC Buttler (wkt), WB Rankin, JC Tredwell, NRD Compton, ST Finn, CR Woakes.