By Matthew Allen BBC Sport Online

How different things might have been had the injury problems evened themselves out earlier on in the Ashes series.

Darren Gough and Andrew Flintoff were unable to play any part for England.

Simon Jones lasted less than than one session, while John Crawley, Andrew Caddick and Alec Stewart have all missed Tests.

By contrast, Australia had a full-strength squad for the first three Tests before Shane Warne dislocated his shoulder in a one-day game.

That did not stop them establishing a 4-0 lead in the next game.

But the absence of Warne and Glenn McGrath (side strain) from the Sydney Test has left Australia in the rare position of being on the back foot and struggling to stay in the match.

Warne bowled Gatting with his first Ashes ball

Without Warne and McGrath, they have assumed a vulnerability that has allowed two English batsmen to pick up centuries in a Test for the first time in the series.

Stuart MacGill and Andy Bichel are decent replacements, but they do not have the same effect on England as Warne and McGrath as either wicket takers or in applying control.

Warne established his psychological hold over a series of English batsmen when he bowled Mike Gatting with his first delivery in an Ashes match in 1993.

Career-best figures of eight for 71 in Brisbane a year later increased a stranglehold over England that has netted him 132 wickets at a miserly average of 23.03.

McGrath had a quieter start to his Ashes career, but a remarkable eight for 38 at Lord's in 1997 set him on his way to 117 wickets at 20.03 against the old enemy.

Successive England captains have denied that their batsmen feared the duo, but Melbourne and Sydney have highlighted their importance to Australia.

In fact, Australia in the fifth Test have looked a different team from the one that demolished England in the first three matches.

Australia won by 384 runs in Brisbane, an innings and 51 runs in Adelaide and by an innings and 48 runs in Perth to wrap up the series.

Bichel is good - but not a McGrath

But, without Warne in Melbourne, they were pushed hard before eventually winning by five wickets after letting England score 387 in their second innings.

Without both star bowlers in Sydney, England compiled their highest first innings score (362) of the series, and continued to look much more comfortable in their second.

"Warne and McGrath have 900 odd Test wickets - they obviously miss them," Vaughan said.

In the past Australia have been accused of switching off in a dead series, but this time they are chasing their first 5-0 Ashes whitewash since Warwick Armstrong's all-conquering side in 1921.

There can be little doubt that the absence of Warne and McGrath has played a big part in Australia losing their dominance this time.

It shows that Australia can be vulnerable with key components missing.

And it raises the question of what will happen when the world champions start having to rebuild a team in which many of the players are on the wrong side of 30.