Clarke, who made 80, and Mike Hussey (44 not out) had fought a desperate rearguard action after England declared on 620-5 with a first-innings lead of 375 in the morning.
England took three Australian wickets after lunch and the Adelaide rain provided only an hour of respite for the hosts as they looked to the skies to help them avoid an innings defeat.
Pietersen, who had completed his career-best innings of 227 in the morning, was giving the specialist bowlers some rest as the day drew to a close when he made another crucial intervention.
Clarke initially walked when Alastair Cook took the catch but returned to his crease as the decision was reviewed by TV pictures. He was walking again when they clearly showed the ball hit the face of his bat.
Text: Reuters
Images: AP
Image: England's Kevin Pietersen, right, celebrates as Alastair Cook, foreground, catches Australia's Michael Clarke, unseen, out on day four of the second Ashes cricket test in Adelaide, Australia, Monday, Dec. 6, 2010. At stumps Australia are 4 for 238 chasing England's 620 runs. Australia's Michael Hussey is at left in background.
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