Mitchell Johnson's pace and bounce has once again rattled the tourists, with captain Alastair Cook undone by a ferocious bumper early on Day Four after Michael Clarke's surprise declaration left England chasing 531 for victory in Adelaide. Australia's Mitchell Johnson (2nd R) celebrates capturing Alastair Cook's wicket. AUSTRALIA has made a surprise declaration before the start of day four, leaving embattled England a target of 531 to win the second Ashes Test at Adelaide Oval. Captain Michael Clarke's decision left opening batsman David Warner stranded on his overnight score of 83, with Steve Smith unbeaten on 23 in Australia's score of 3-132. Clarke's decision - which might have been prompted by the threat of rain today - gives Australia two full days to bowl England out. England's task looks beyond it, with the tourists having made a combined total of 487 runs in their previous three innings this series.