Two Ashes series or one?
Imagine a Champions League tie in which the result of the first leg has no bearing on the second. A Tour de France which at the halfway point sends every participant back to level pegging. Or a boxing match where all points up to round five are deducted from the final ledger. All these fanciful-sounding scenarios approximate roughly to what Australia and England are about to go through. Ten Test matches spread across two series, five in the UK, five in Australia. Regardless of what happens in the first five, it will be the winners of the second quintet who keep the urn or its replica.
The unusual nature of the contest about to begin at Trent Bridge is not without precedent. It was common back in the days when Australia contested England and few others, and last took place as recently as the mid-1970s. But the evolution of the cricket calendar into a veritable snakes and ladders board of formats, nations and brief Test series makes this sequence highly unique, and likely to take a high toll on its participants.
For England, the dual series shape as a potentially crowning moment for many of their players, from the captain Alastair Cook and the batsman Kevin Pietersen to their seasoned bowling spearheads Jimmy Anderson and Graeme Swann. Save for Cook, who appears likely to still be batting for England by the time the 2020 Olympics are held in Istanbul, Madrid or Tokyo, the others may be tempted by the thought of leaving on top of successive Ashes victories.
Among Australia's ranks, there will be similar ambitions for a handful of players, including Brad Haddin, Ryan Harris and even the captain Michael Clarke. Returning the urn, as Cricket Australia's preferred slogan for the Ashes Tests intones, is the kind of parting gift many players have desired for their careers, not least Justin Langer, Glenn McGrath and Shane Warne when they heralded the start of Australia's decline by demobbing en masse in 2007.
But it is also impossible to ignore the fact that a confrontation fought over 10 Tests, eight of them scheduled in the back-to-back style now favoured by administrators but loathed by anyone who either plays in them or has to monitor the physical wellbeing of those who do, will result in more than a few casualties. The majority of these are likely to be among the fast bowlers, a breed undervalued next to their batting counterparts in part because of the inherent cost of what they do.
England and Australia have both worked assiduously in recent years to build crops of fast bowlers capable of weathering harsh elements and schedules. It is now a matter of course for Australia to have five fast bowlers on call at any given Test match, and in the case of this tour the inclusion of James Faulkner has provided Darren Lehmann and his fellow selectors with six. It is in terms of such depth that the Australians have their best chance of outlasting England, probably over five matches but almost certainly over 10.
Apart from James Pattinson, Mitchell Starc, Peter Siddle, Ryan Harris, Jackson Bird and Faulkner, the Australian fast bowling stable can also boast of Mitchell Johnson, Ben Hilfenhaus, Nathan Coulter-Nile, Josh Hazlewood, Chadd Sayers, Luke Butterworth and that 20-year-old long-term project Pat Cummins. Even the likes of Luke Feldman, sometime Test player Trent Copeland and the South Australian Gary Putland possess quality not terribly far removed from international standard.
By comparison, England's pace bowling resources are a little more modest, and the reliance on Anderson in particular to maintain his fitness is heavy. For this reason, the outlook for Cook's team is best in the short-term. A series at home during what shapes as an English summer of generous sunshine and newspaper headlines about "scorching" 29C days will more than likely result in a third consecutive panoramic image of the urn being lifted by England while The Oval rejoices. But the longer view suggests that provided Australian noses are not too bloodied by the encounter on foreign shores, they may be better equipped to stay strong throughout the second instalment of the series down under.
Certainly this is the sort of pragmatic view that has emanated every so often from Cricket Australia's camp, though never in terms so blunt as to publicly say "put on a good show in England and we'll get them on the home leg". It was somewhat instructive to witness Clarke, Starc, Shane Watson and others playing cricket on a barge next to the Tower Bridge in London after the Champions Trophy, not to promote this Ashes series but to sell tickets for the next one. CA's hope is for a return to lasting supremacy over England, and should this take two series to set in motion rather than one, it will still have been worth the planning.
In this there are parallels less with 1989, when a building Australian team thrashed England not in contradiction of their own expectations but those of a UK press that had largely ignored the recuperation of the Antipodean game under Allan Border and Bob Simpson since 1987, but 1972. On that occasion a young Australian side led by a dynamic leader in Ian Chappell arrived in England without much serious expectation of defeating what was then acknowledged as the best team in the world.
Spearheaded by a battery of pace bowlers that included not only Dennis Lillee but also Bob Massie, David Colley and Jeff Hammond, Chappell's side surprised Ray Illingworth's men by fighting back twice from a deficit to square the series 2-2. They had not won the Ashes, but had tilted the balance. Two years later, their stocks augmented by Max Walker and Jeff Thomson, Australia would carry that momentum to victory at home.
Forty years on, Australia have again taken a young side stocked with fast bowlers to face a far more accomplished England. They may not win the Ashes immediately, but they can certainly set themselves up for a grand finish - the SCG next January cast as their Wembley, Champs Elysees, or Madison Square Garden.
Daniel Brettig is an assistant editor at ESPNcricinfo. He tweets here