Smith leads Australia revival after first innings in fifth Ashes Test
Australia were eventually bowled out with what became the last ball of the second day for 295, 12 runs ahead of England's 283.
It looked as if England would enjoy a sizeable advantage as veteran seamer Stuart Broad sparked a slump that saw Australia decline from 115-2 to 185-7.
But Smith and Australia captain Pat Cummins (36) kept England at bay during an eighth-wicket stand of 54. Cummins then added 49 for the ninth wicket with Todd Murphy.
Off-spinner Murphy - recalled following last week's rain-marred drawn fourth Test at Old Trafford - added to England's woes with a sparkling 34 off just 39 balls.
Cummins eventually holed out off part-time spinner Joe Root, with rival skipper Ben Stokes throwing the ball back in over the rope at long-on to complete a fine catch.
'Ebbed and flowed'
Australia, as the holders, are assured of retaining the Ashes at 2-1 up, and only need to avoid defeat at The Oval to secure their first Test series win away to England in 22 years.
"It's ebbed and flowed the whole way, we're pretty disappointed," Smith told the BBC.
"A few of us got good starts but couldn't go and get a big score. Twelve runs in front, it's a one-innings game from here pretty much."
Australia resumed on Friday on 61-1, with Usman Khawaja 26 not out and Marnus Labuschagne, fresh from his hundred at Old Trafford, unbeaten on two.
Their position in the series means they have no need to replicate England's risky 'Bazball' batting approach.
But they arguably veered too much in the opposite direction during an attritional morning session, scoring just 54 runs in 26 overs for the loss of Labuschagne, who edged express fast bowler Mark Wood to Root in the slips, who took a brilliant one-handed catch.
But Broad, whose 167-Test career has been notable for dramatic wicket-taking bursts, soon reduced them to 127-4.
He had Khawaja, the leading run-scorer in the series, LBW for 47 with a full-length delivery.
Broad, who made his name in Ashes cricket with a return of 5-37 at The Oval in 2009, became the first Englishman to take 150 Test wickets against Australia.
That rose to 151 wickets when Travis Head was caught behind off an excellent delivery that nipped away off the seam.
James Anderson, Test cricket's most successful pace bowler, then took just his fifth wicket of the series when Mitchell Marsh played on.
"It's a very level game," said Anderson. "Getting into the position we did, we're a little disappointed they got past us. Pat and Murphy batted really well in the end."
England were a bowler light on Friday as Moeen Ali remained off the field with the groin injury the off-spinner suffered while batting on Thursday.
But Root filled the gap when inducing an ugly swipe from Alex Carey that went straight to Stokes at short cover.
Australia were 185-7 when Mitchell Starc holed out to backward square leg off Wood.
Smith had made 43 when, going for a needless second run, it appeared he had been beaten by a throw from substitute fielder George Ealham to wicketkeeper Jonny Bairstow.
But third umpire Niton Menon, after several minutes' study, ruled in the batsman's favour.
England took the new ball but Smith completed a 98-ball fifty when he drove Broad for a fine boundary.
It looked as if the former Australia captain, whose four previous Tests at The Oval had yielded three hundreds, might go on to three figures again until he carelessly skied a catch off Chris Woakes to Bairstow.
Murphy, however, pulled Wood for three fine sixes, with the left-handed batsman also square-driving Woakes for a stylish four.
Woakes eventually had the 22-year-old, in only his 14th first-class match, LBW but the damage had been done.
