Irrespective of what happens in the next two days of the 3rd test, this is the side I would field for the 4th test:
1.Phillip Hughes
2.Simon Katich
3.Ricky Ponting
4,Shane Watson
5.Michael Clarke
6.Mike Hussey
7.Brad Haddin
8.Mitchell Johnson
9.Nathan Hauritz
10.Brett Lee/Stuart Clark
11.Ben Hilfenhaus
Its imperative that we win or atleast give ourselves the best possible chance of winning at Headingley, and that's why I think we need to a bit of a risk when it comes to picking the playing XI..
Phil Hughes has had his fair share of problems on this tour, but still I see him as a bloke who could provide Aussie batting line-up with that bit of x-factor, which is so badly needed atm.
Pushing Hussey down to no.6 would also be worth the try, things aren't going well for him atm, but he has the ability to stabilize the innings in case of a top-order collapse, and he also can bat decently with the tail, and Watto batting at 4 will have the freedom to play his shots and be aggressive.
Would stick with Johnson for pretty similar reasons I gave for Hughes, Mitch is a match-winner, and judging by his spell yesterday evening, he seem to be slowly but surely getting into some sort of a rhythm, and persisting with him for the next test is a risk worth taking.
Would also play either Lee or Clark instead of Siddle, need some experience in the bowling attack, which either one of them could provide.
Still rate Siddle and North pretty highly, and its kind of harsh on them if they are dropped, but they really haven't done that well either to secure their places in the side, and with Ashes at stake, some ruthlessness has to be shown.
Though having said all this, won't surprise me one bit if we play with an unchanged side at Headingley.