Fourth Ashes Test preview

The 2009 Ashes begins its final Act on Friday when the fourth Test gets under way at Headingley. For the first time the series is up for grabs: England regain the urn with a win - and would do so in emphatic fashion; any other outcome ensures that it will climax in the shadow of Kennington's gas tower once again, almost certainly earning epic status in the process.

The high stakes are self-evident. The Leeds ground has produced a positive result for ten consecutive Tests and an eleventh would either hand one team the Ashes or put another in strong control. (England do not need telling that it is nice enough to play an Ashes Test at the Oval when a draw suffices). More than that, it has the potential to define the contest for years to come. If England win then they will do so in handsome terms and expect to enter future series as favourites, even Down Under. If Australia peg them back then the message to the Poms is unequivocal and humiliating: with a poor team, playing badly, enduring bad luck and on your own turf, still we have enough to get on top.

Australia have had the worse of the last two Tests while drawing encouragement from the final day at Edgbaston. England's bowlers, for whom Andrew Flintoff was largely a passenger, were blunted by a rearguard action from Michael Clarke and Marcus North. It hardly guarantees a change in series momentum but has fostered hope after a torrid period for the visitors.

Ricky Ponting sprang a surprise in Birmingham, sacrificing Philip Hughes to save Mitchell Johnson. Shane Watson did well as a replacement batsman but was hardly a convincing fifth bowler to cover the left-armer's shortcomings. It is still up to Johnson to lead Australia to 20 wickets and he hinted at resurgence last weekend.

Australia's case would be strengthened further with the return of wicketkeeper Brad Haddin, injured in the Edgbaston warm-up. Stand-in Graham Manou is an accomplished gloveman but perhaps fortunate to bat even above Johnson whereas Haddin is a potential Test number six. As such, the chance to ape England's five-and-five balance is available to Australia but it seems certain they will persevere with Watson even if Haddin passes a late fitness test.

This in itself is an indication of growing confidence since, with Brett Lee and Stuart Clark on the sidelines, Ponting could put together an imposing five-man attack if inclined to gamble. Ben Hilfenhaus continues to impress but Peter Siddle will have to make way for Lee if the veteran is fit.

Lee has a far more modest Ashes record than his reputation might suggest and is most impressive as an ODI bowler. Nevertheless his explosive power, evidenced in running through the England Lions a week before the Cardiff opener, will be a welcome weapon to Ponting, who has looked short of ammunition all summer. It further hints at a swing back towards the tourists - they are welcoming men in as their opponents lose them - and crucially threatens the home lower order. Flintoff, Stuart Broad, Graeme Swann and James Anderson have added vital runs but none is comfortable against extreme pace. While the anticipation will surround Lee on introduction against the top batsmen, it is in the second half of the innings that he is most likely to prove decisive.

There are rumours that Clark might return instead of Hilfenhaus or even Nathan Hauritz, who has done exceptionally well but may not find Leeds to his liking. However that is