England will have to bat for more than five sessions on a wicket already scarred with cracks to save the test and prevent Australia from taking an unassailable 3-0 lead in the series to reclaim the Ashes.
The hosts had resumed at 235 for three with Watson on 29 and the big all-rounder signalled his and his team's intent by smashing two fours and a six off the first over from spinner Graeme Swann.
Watson's departure for 103 was as remarkable as his innings, which included 11 fours and five sixes. Ian Bell dropped his skied shot but the batsman had given up and bowler Tim Bresnan ran him out at the non-striker's end.
George Bailey (39 not out) smashed James Anderson for 28 off an over to take Australia's lead past the 500-mark and captain Michael Clarke called his players in.