London - Shane Watson was in sight of only his third Test hundred as Australia dominated the first session of the Ashes finale at The Oval on Wednesday.
Australia, who at 3-0 down were trying to avoid a first Ashes series without a Test win since 1977, were 112 for one at lunch.
Watson was 80 not out, his best score of a disappointing series where he'd previously only managed one other fifty, and opener Chris Rogers unbeaten on 21 after the early loss of David Warner.
Watson was especially severe on England's two debutants, striking six fours apiece off seamer Chris Woakes and left-arm spinner Simon Kerrigan, whose first two overs in Test cricket cost an expensive 28 runs.
It was no surprise when Australia captain Michael Clarke chose to bat first on a typically good Oval pitch, with sunny skies also in the batsmen's favour.
But England had an early breakthrough when left-hander Warner played a loose shot outside off-stump to James Anderson and was caught behind by wicketkeeper Matt Prior for six to leave Australia 11 for one.
Anderson's 325th Test wicket saw him draw level with Bob Willis in second place in an England all-time list headed by Ian Botham with 383 wickets.
Warner's exit brought all-rounder Watson to the crease.
Having started the series as an opener, Watson later appeared at number six and this match saw him filling Australia's problem position of number three after Usman Khawaja was dropped.
Watson, who has scored just two hundreds in 45 previous Tests and has often been out lbw, survived an early leg before appeal from Anderson.
But with England's bowlers failing to gain much movement, Watson was able to hit through the line with confidence.
Meanwhile, the first-day pitch was not providing excessive turn for an England side featuring two spinners in Kerrigan and Graeme Swann.
Indeed, Watson advanced to drive experienced off-spinner Swann for six during a 61-ball fifty also including nine fours.
Both teams made changes following England's 74-run fourth Test win at Chester-le-Street, with the hosts missing injured all-rounder Tim Bresnan and dropping out-of-form batsman Jonny Bairstow.
looking for their first win in nine Tests, gave a debut to all-rounder
James Faulkner in place of Khawaja, with Mitchell Starc recalled after
Jackson Bird was dropped.