Hugh Godwin: Question time for Jones as his champions show unfamiliar failings

How to place a precise value on home advantage? It would be easier to split an atom with a sledgehammer. The worth to Australia of this win - which might have been different if the match had been in Limerick not Melbourne - was probably a fortnight's grace for the first World Cup holders to have the luxury of defending the trophy on native soil. Even that might not be enough to preserve until the last the interest of a team racked by selectorial uncertainty and falling short in departments where they were once so strong.

In anyone's assessment the Wallabies will be expected to see off Scotland in their quarter-final in Brisbane next weekend, before facing New Zealand or South Africa in the last four. But the pundits are massing to have a go at Eddie Jones, principally on the matter of the Australia coach's choices of personnel in the midfield and back three. "Is he picking the right side?" asked Mark Ella after the nail-biting conclusion to Pool A. "Can they go on and win the World Cup? I'm not sure they can."

Another treasured veteran of the No 10 jersey, Michael Lynagh, was equally on edge. "There was some negative decision-making by George Gregan," Lynagh said of Australia's captain and scrum-half, who partnered Stephen Larkham in the pivotal half-back roles for a record-equalling 47th time. It should be borne in mind that calling a fellow Aussie negative is the worst kind of insult Down Under. They do not go in for backward steps. That sort of thing is supposed to be for whingeing Poms.

So, to the ranks of their principal rivals, a dose of Wallaby frailty is unusual, and most welcome. We admired but did not particularly revel in the way their aggressive defence earned them the top prize in Cardiff four years ago. In the intervening period, the lessons in snuffing out an opposition backline have been taken to heart by the likes of Phil Larder with England and David Ellis in France. But all the while it was reasonable to expect from the men in gold the occasional 24-carat piece of back play. The legacy of Ella and Lynagh was safe with Larkham and Joe Roff, Gregan and Matt Burke. Or so we thought.

Perhaps Roff had an off day against the Irish. A master of the wing's arts, his enduring gifts permit him that verdict. The question is whether Roff is being best served by the combinations around him. The Gregan-Larkham double act is running short of new material, and maybe Matt Giteau should be allowed to write a new script. Burke has passed the goal-kicking duties to Elton Flatley, and switched positions, too, to outside centre. At full-back, Mat Rogers, the ex-rugby league international, is engaged in the same tricky process as Wendell Sailor and Lote Tuqiri: that of teaching new dogs old tricks.

Sailor, a bull of a man with ball in hand, looks extremely uncomfortable in defence, an incongruous state of affairs given Australia's recent history. As a substitute, Tuqiri replaced Burke when Sailor ought to have been booking his passage to the touchline. The suspicion is that Jones, having placed his faith in cross-code converts, is living on a prayer.

Not that it is easy to judge the coach's mood; Jones's monotonous pronouncements safely conceal displeasure and delirium alike. But television pictures showed him guzzling enough water to fill Sydney Harbour, so perhaps the heat is on.

Sailor will be targeted by the Scots, who after all do not have many areas of encouragement of their own to seize upon, and certainly by whoever emerges from the All Black-Springbok set-to.

A recall for Stirling Mortlock at centre could be on the cards, and Rogers might be better off on the wing - these and others all add up to many more imponderables than are generally associated with prospective World Cup winners.

Another point of Australian discomfort was the line-out, where Ireland's Paul O'Connell and Malcolm O'Kelly tormented their opposite numbers, Nathan Sharpe and David Giffin. It was a reminder of the huge gap left by the retirement of John Eales. "Nobody", they called the elastically-limbed former captain, as in "Nobody's Perfect", and Sharpe and Giffin inevitably suffer by comparison. Nobody, you might say, did it better.

In victory, Australia were immensely indebted to George Smith, whose presence alongside a fellow openside, Phil Waugh, is yet another debatable option. Smith popped up at the front and tail of the line-out, snaffled Irish ball at the ruck, filled in at the back of the scrum when David Lyons was substituted, and still managed to make the extra man to score Australia's first half try. He also laughed off the most comical moment of the World Cup, when Brian O'Driscoll tacked him by the hair. Alas, for Jones, not even Smith can play everywhere.