Alastair Cook fell 10 runs later, caught by Michael Clarke off Ashton Agar for 50 in 165 balls.
But it couldn't last, and Pietersen was bowled by James Pattinson for 64.
Ashton Agar's game of his life continued when he picked up the wicket of Jonny Bairstow.
Matthew Prior fell to Peter Siddle as Australia sensed a chance of bowling England out cheaply.
Meanwhile, at the other end, Ian Bell played a superb innings of 95 not out to boost England.
Michael Clarke was less than impressed on what turned out to be a tough day for him.
Broad made it through to stumps on 47 but few were talking about the runs he scored...
The moment that got everybody talking. Broad edges, Clarke catches, Broad survives.
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