At Friday´s close Ashes-holders England were 52 for two in reply to Australia´s first innings 527 for seven declared, a deficit of 475 runs, in a match the tourists, 2-0 down with three to play, had to win to stand any chance of regaining the urn.[break]
England captain Alastair Cook, dropped on 15, was 36 not out and Jonathan Trott two not out after Clarke, whose innings was his highest against England, enterprisingly declared not long after tea.
Aggressive seamer Siddle was, surprisingly, the fifth of five bowlers deployed by Clarke.
But he responded by taking two wickets for two runs in 12 balls.
Siddle removed Joe Root, fresh from his 180 in England´s crushing 347-run second Test win at Lord´s, with the opener caught behind for a painstaking eight off 57 balls.
He then had nightwatchman Tim Bresnan well held by wicketkeeper Brad Haddin.
Replays showed Bresnan hadn´t made contact, the ball hitting his trousers, but, following consultation with Cook, there was no review.
"Bres thought he hit it, he heard a little noise and assumed it was an edge. So he walked," explained Graeme Swann, who led England´s attack with five wickets for 159 runs in 43 overs -- the 17th ´five for´ of the off-spinner´s 55-Test career.
Australia came into this match on the back of six straight Test defeats -- their worst run since 1984.
Star batsman Clarke, rather like Allan Border at the start of the Australia great´s captaincy career in the mid-1980s, has often had to compensate for the weaknesses of his top-order colleagues.
Yet his Test-best against England was also his 10th century in 27 Tests as captain, with his average as skipper of 65.15 well above his career mark of 52.52.
"All the boys should be really proud to make over 500 and then come back out in the field and get some early wickets," Clarke said.
"How good was my innings? Ask me in three more days. If we win then it´s a good innings. If not, it´s a waste of time. It is always nice to make a big hundred but we´ve got three more tough days to go."
And the tongue-in-cheek Swann insisted all was not lost for England.
"We will bat all day tomorrow (Saturday) into day four, get a lead then bowl them out. I see you laughing but I don´t see why we shouldn´t approach this with any fear. We´ve got some of the best batsmen in the world."
Australia resumed on yet another sunny day well-placed on 303 for three with Clarke 125 not out, after scoring the tourists´ first century this series, and Steven Smith 70 not out.
Clarke, on 136, drove uppishly off Bresnan only for Swann, very close in at short extra-cover, to parry the fast-travelling chance above his head.
A single then saw Clarke, who won the toss, surpass his previous highest Test score against England of 136 at Lord´s in 2009.
But a stand eventually worth 214 ended when Smith on 89 top-edged a slog off Swann to Jonny Bairstow at midwicket, leaving Australia 343 for four.
New batsman David Warner was booed by spectators, having missed the first two Tests after being banned for punching Root in a Birmingham bar in June.
Warner did not stay long, the left-hander out for five when an edge off Swann deflected via wicketkeeper Matt Prior´s thigh to Trott at slip.
Warner requested a review, despite a clear nick, and, with replays conclusive, he walked off to yet more jeers.
Clarke´s more than seven-hour innings of 314 balls with 23 fours ended when, cramped for room, he played on to Stuart Broad as the paceman took his 200th Test wicket.
But Haddin, dropped on 10 by Prior off James Anderson -- who went wicketless on his Lancashire home ground -- before making 65 not out, and Mitchell Starc, whose 66 not out was worthy of a top-order batsman not a tailender, added an unbroken 97 for the eighth wicket.
Clarke brought on off-spinner Nathan Lyon, recalled after Australia dropped teenager Ashton Agar following the slow left-armer´s wicketless match at Lord´s, in just the seventh over.
Lyon almost had a wicket with his third delivery when he took Cook´s outside edge only for the ball to hit Haddin on the leg, when the wicketkeeper should have done better, with Clarke unable to grasp the rebound at slip.
"Hopefully Nathan Lyon can continue to bowl like he did this evening because he bowled extremely well," said Clarke.
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