Australia have gained control of the third Ashes Test by taking two key wickets after tea on day two in Perth.
England reached stumps 205 runs behind the hosts on 180-4, after losing Alastair Cook and Kevin Pietersen in the day's final session.
Captain Cook departed on 72 when he attempted to cut Nathan Lyon, but miscued straight to David Warner.
That wicket, which came after Michael Carberry (43) and Joe Root (4) had also been dismissed, left England on 136-3.
The tourists then slumped to 146-4 as Peter Siddle got the better of Pietersen once again. Pietersen miscued a pull shot and Mitchell Johnson took a catch diving backwards at mid-on.
Ian Bell (9*) and Ben Stokes (14*) have steadied the ship with an unbeaten partnership of 23, but Australia's bowlers will fancy their chances of securing a significant first-innings lead when play resumes tomorrow.
Day two had started brightly for England and the morning session belonged to the tourists' bowlers, as, after resuming on 326-6, Australia were skittled out for 385.
A Stuart Broad bouncer got rid of Johnson (39) in the second over of the day, with the local favourite edging to Matt Prior.
Prior then took another smart catch to dismiss danger man Steve Smith (111) off the bowling of James Anderson, with Hotspot confirming a feint inside edge.
Ryan Harris survived 19 balls before clubbing a thick edge to Root at gully, leaving Australia nine down on 354.
Siddle (21) and Nathan Lyon (17*) frustrated England somewhat with a final-wicket stand of 30, but the innings eventually came to an end when the former edged to Prior.
England's reply got off to a fine start, with Cook and Carberry providing an 83-run opening partnership.
However, Carberry was dismissed softly by Harris when the Hampshire batsman pulled out of a shot at the last minute and saw the ball deflect onto his stumps via an inside edge.
England were then rocked by the controversial loss of Root's wicket. Shane Watson swung a pacy delivery past 22-year-old's bat and the ball carried to Brad Haddin, who led the appeal.
The umpire's finger went up, but Root was adamant that he had not made contact and the tourists immediately referred the decision upstairs.
Neither Hotspot nor Snicko provided any conclusive evidence to show that Root had hit the ball, but, because there was also no proof that the umpire had made the wrong call, the decision was not overturned.
That moment swung the match in Australia's favour and the hosts' momentum continued as Cook and Pietersen were removed.