ALASTAIR Cook scored his second successive century as England finished on 317 for two to give themselves a great chance of taking a 1-0 lead in the Ashes series after the second day of the second Test against Australia.

Cook finished the day on 136 not out with Kevin Pietersen looking ominous on 85 as the pair shared an unbeaten stand of 141 to leave England with a 72-run lead at the Adelaide Oval.

Cook scored 17 boundaries in his 246-ball stay at the crease while Pietersen cracked 13 fours as he moved within sight of his first century for 21 months.

Pietersen has not scored a ton since his effort in Trinidad against West Indies in March 2009 but he is on the brink here with England dominant despite the near instant loss of captain Andrew Strauss in the first over for a single as they replied to Australia's under-par 245.

Pietersen joined Cook at the crease after the Essex opener had shared a second-wicket stand of 173 with Jonathan Trott, the Warwickshire batsman going just before tea after making 78.

Pietersen, with the quickest 50 of the match from 77 balls, was the ideal new foil to Cook.

The pair moved swiftly on to their century stand, Pietersen powering a cover drive to the boundary to take the pair on to 103 with England 34 ahead.

While Cook was organised and determined, Pietersen kept up the tempo and a boundary took England past 300.

Ryan Harris unsuccessfully appealed for lbw against both men, although he did not go to review on either occasion, and Australian heads were down at the end of another glorious day for the visitors.

England had not made the best of starts, Strauss choosing to leave the third delivery of the day, a length ball from left-armer Doug Bollinger, only to see it remove the off bail.

He was therefore gone for just a single. But that did not alter the consensus England had given themselves an outstanding chance to go 1-0 up in the series, after bowling Australia out for an under-par score at a venue traditionally associated with 500-plus first-innings totals.

Trott came to the crease and he and Cook spent most of the first two sessions continuing their torment of Australian bowlers.

Trott eventually went shortly before tea. But Cook retained an appetite for more, on the back of his first Test double-century.

Trading especially heavily on the cut shot whenever Australia give him the necessary width while picking the bowlers off through the legside when they got too straight, he reached his hundred with another cut off Xavier Doherty for his 15th four from 171 balls.

Cook and Trott famously piled up a record 329 last week in Brisbane - and when England's number three was finally out here they had put on 502 together in almost 10 previously undefeated hours.

There was some good fortune along the way for Trott. But as for much of his unbeaten 235 at the Gabba, Cook was chanceless.

They nonetheless had a new challenge to face in the shape of Bollinger and Harris' new-ball partnership.

Neither was in the Australia side last week, yet they were asked to open the bowling here - and looked threatening for a time on this pacy pitch.

Australia missed their chances to put England in almost as much trouble as they themselves had unexpectedly encountered 24 hours earlier.

With Strauss gone, Trott might have been run out for six as he scampered back from an aborted single. But Doherty missed the stumps from square-leg - unlike Trott himself, who had seen off Simon Katich in similar circumstances on day one.

Michael Hussey then dropped a regulation catch low down in the gully when Trott, on 10 this time, failed to keep an attempted drive at Bollinger on the ground.

Opener Cook had to wait for his scoring opportunities, and it was not until Peter Siddle replaced Bollinger at the River End that he counted his first boundary - an off-drive from the 35th ball he faced.

Trott was runless, on 37, for almost 40 minutes and 23 balls. But if Australia were hoping to beat the England number three in a patience test, they had surely picked the wrong man.

So it proved with a flurry of boundaries from both batsmen straight after lunch.

Australia resorted to testing Cook, in particular, with a succession of short balls and three men out on the hook.

They fleetingly thought they had the breakthrough when Cook aimed a hook at a good bouncer from Siddle and was given out caught-behind on 64 by Marais Erasmus. An immediate decision to review was vindicated, however, replays showing the ball hitting only Cook's shoulder.

Trott had his third 'life' when Brad Haddin dropped a regulation caught-behind chance down the legside from a mis-hook off the glove at Harris. But he was gone two runs later anyway, his favourite back-foot punch to midwicket aerial this time and well-caught by Michael Clarke off the same bowler.

The third-wicket pair of Cook and Pietersen then eased England into the lead and with huge power to add and time on their side, despite an uncertain forecast, to try to force a precious victory.