Kevin Pietersen admitted England face a battle to keep the Ashes alive after collapsing in the third Test.
Pietersen admitted England face a battle on day three
Pietersen, who made 70 of the tourists' 215 on day two in Perth, was in despondent mood at stumps.
He said: "On some days we've played fantastic cricket [but] we make it difficult for ourselves on occasions. We never do things the easy way.
"It was a difficult day - we've had some very difficult days and it looks like there's going to be another."
Australia will go into day three looking to build on their current a lead of 148, with nine wickets in hand and both Ricky Ponting and Matthew Hayden settled.
Already 2-0 up in the series, victory for the hosts here would confirm the return of the Ashes urn to Australia.
"We've got to try and hit our straps, be as patient as we can and make sure Australia have to fight for every single run with the lead they've got," Pietersen promised.
"We'll come back and we'll come back fighting. It's a pretty good batting wicket so you never know."
Pietersen provided the backbone of the England innings, helping to add 138 in seven different partnerships, although he exposed several lower-order men to the strike.
His dismissal finally came from a loose drive at Brett Lee but he said: "I'm never happy getting out but I was going to get out at some stage.
"I could have got out for 30, 40. I'm happy with 70."
After Pietersen fell, Monty Panesar joined Steve Harmison in a last-wicket stand of 40, ending unbeaten on 16.
Panesar, previously passed over for selection because of perceived poor batting, impressed observers especially with a shot off Stuart Clark.
"He plays a few extravagent shots but that on-drive - I still dream I could play the game like that," Pietersen added.
"Monty's definitely got the hand-eye coordination with the bat in his hands. He sets up well and he's a crowd-pleaser."