The captain's 187 was his highest score abroad, his first at No.4, and changed the tone of a campaign that looked to have slid well and truly off the rails at Lord's a fortnight ago.

It helped Australia get to a hefty 7-527 before Clarke declared, and on Saturday there was more early cause for optimism when England lost two wickets to slump to 4-110 after Jonathan Trott (five) and, crucially, his rival captain Alastair Cook (62) were sent packing before lunch.

Cook's exit, 15 minutes before the break, was sealed via a brilliant catch from wicketkeeper Brad Haddin, diving at full stretch to his right. The England captain had plodded along efficiently in the morning and seen of many better balls than the one that unseated him.

It was delivered by Mitchell Starc, and was short, pitched on leg stump and was custom-made to tuck behind his pads. However, the captain's attempted glance only caught an edge and Haddin, at 35 and not long ago written off as a Test gloveman, produced a grab from out of the top drawer.

Starc's breakthrough followed Peter Siddle's double blow the previous day, removing opener Joe Root and nightwatchman Tim Bresnan in quick succession, and the removal of Jonathan Trott earlier in the first session on Saturday by Ryan Harris gave Australia a commanding advantage.

England trailed by 408 runs at lunch, needing 209 more to avoid the follow-on. Harris had left the ground on Friday, feeling unwell, but after a night's sleep was back steaming in from the pavilion end, and sent Trott on his way after an unconvincing tenancy in the middle. The South African-born No.3 fended the sturdy fast bowler indecisively towards Clarke, who completed a sharp low catch at second slip.

There was anything but a shortage of intent about Kevin Pietersen (33 not out) before lunch, however. After a nervous start against Harris, he turned entertainer, and in direct contrast to the steady approach of his captain Cook produced shots more out of the Twenty20 how-to guide than the Test handbook.

Australia, unquestionably on top as they sat down to eat on the third day, has managed a turn in fortunes at Old Trafford, helped greatly by Clarke's mighty contribution.

The captain will not weigh his best score out of Australia against his other major achievements - the triple century, and the three doubles at home - until the match is over.

''I don't want to compare, to be honest,'' Clarke said. ''I think I'll be able to assess it more if we win the Test match. I've said for a long time it doesn't matter how many hundreds you get, if you're not winning games of cricket they're irrelevant, so if we win this test match I'll be extremely pleased.''

Clarke said many would ''still be laughing'' at his belief Australia could turn around a 2-0 series deficit, but the response from its heavy defeat at Lord's had shown character.

''The team should be extremely proud of the position we are in,'' he said after day two.

''There is still a lot of work to do. The wicket is pretty flat and there is not much movement for the bowlers. Hopefully we get a second innings as well so we will have to bat well there as well.''

The captain's efforts with the bat also had the statistical gurus in a lather.

Clarke's 187 made him only the second Australian, after Don Bradman, to be out on that score in a Test match. It is not the first time his name has been mentioned in the same breath as Bradman's in a prolific past year or so.