Oldham's proud unbeaten away record this season ended, in effect, in the 54th minute as Scott Murray, Bristol City's Scotland B winger, scored the finest individual goal seen as Ashton Gate for years.
He picked up the ball in his own half, rounding off a 90-yard run with a calm shot wide of Les Pogliacomi.
Home boss Danny Wilson was in no doubt about its exceptional merits: "It takes its place in the top echelon of goals. The finish was sublime and composed." Until that strike, Oldham had looked capable of absorbing the pressure from the always livelier and more constructive City side. But the visitors' manager, Iain Dowie was far from pleased: "It was our worst display for a long time. The unbeaten run was still a fantastic achievement." Bristol made absolutely sure in injury time when substitute Christian Roberts received the ball from the versatile Murray to race forward for a second goal.
The West Country crowd gave an ovation at the end to their team in this play-off tussle.
Oldham would have been behind at the interval but for the agile skills of keeper Pogliacomi. He made three crucial saves from Mark Robins, on loan from Rotherham and expected to sign permanently following his recent goalscoring flair since coming to Bristol.
Little was seen of Oldham's attack. As they searched for an equaliser midway through the second half, their best chance fell to the busy Fitz Hall.
His header from a few yards went over the bar. A 35-yard free-kick from skipper Dave Eyres also flew marginally wide.
Yet this was City's game, as they produced their best form for weeks.
Tommy Doherty, keeping the experienced Brian Tinnion on the bench until late in the match, was influential, though it was an all-round team performance that was always a step ahead of the more dour Oldham.