Barnsley 1-0 Bristol City
Mark Perrow reports from Oakwell
City fell to a cruel defeat in South Yorkshire thanks to a solitary second half goal.
Jacob Mellis' header five minutes after the interval was enough to claim all three points for the hosts, who were reduced to ten men only two minutes later when Bobby Hassell was shown a straight red card.
City piled on the pressure, finishing with three strikers on the pitch, but substitute Steven Davies was denied by the crossbar from a 90th minute free kick and Barnsley held on.
Derek McInnes handed Sam Baldock his first start after City's newest recruit showed off a glimpse of his talents in a debut cameo against Cardiff City last time out.
His involvement at the expense of Ryan Taylor was the only change from the side victorious over the Bluebirds at Ashton Gate, while Dean Gerken and Richard Foster both missed out altogether with hip injuries.
It only took four minutes for Baldock's first sniff of a chance, and the striker would have been disappointed to clear the crossbar from Mark Wilson's well-disguised low corner.
Jon Stead soon forced Barnsley debutant Ben Alnwick into his first save low to his right, before Craig Davies crashed a curling shot against the post in the home side's first display of attacking intent.
City were still the slicker team in possession but Chris Dagnall stung the palms of Tom Heaton with the Tykes not lacking a goal threat of their own.
Keith Hill's men were certainly growing into the contest, and Heaton was again called upon to keep out Davies' downward header on 26 minutes before midfielder Mellis fired wide.
By the end of the first half, City must have been relieved to keep the clean sheet intact, although Wilson's late 25-yarder reminded Barnsley they still had nothing to show for 30 minutes of dominance.
McInnes responded by withdrawing Albert Adomah at the interval in favour of Marvin Elliott with the intention of matching Barnsley's narrow midfield four.
But five minutes later his side behind anyway, as Mellis headed home Martin Cranie's right-wing cross via the underside of the crossbar.
Within two minutes of the opener, the balance of power shifted when Hassell was dismissed for an ugly lunge on Stead, prompting City to pile on the pressure.
Baldock's snap shot was well held by Alnwick with Stead lurking, before Woolford surged into the box and lobbed the ball over Alnwick only to be denied by a last-ditch intervention from substitute John Stones - brought on to fill the void vacated by Hassell.
Taylor was called upon midway through the second half in place of Baldock, while Stephen Pearson made way for namesake Davies shortly after.
It was the striker's first touch that came closest to an equaliser within seconds of his arrival, as former Nottingham Forest rival Greg Cunningham's inviting cross was headed only inches wide by ex-Derby County man Davies.
Ten minutes from time the same duo combined again but to similar effect as Davies' effort back towards the opposite corner narrowly evaded the upright.
City should have been punished for committing bodies forward in a backs-against-the-wall finale from the hosts' point of view, but Liam Fontaine was on hand to prod Marlon Harewood's toe poke off the line.
Time was running out on City, but Davies struck the face of the crossbar at the death before Heaton saved well from Harewood with his feet on another Barnsley breakaway.