Crewe Alexandra snatched a smash-and-grab win as Lauri Dalla Valle’s late win took the spoils at Oakwell.
The visitors netted the opener against the run of play early on in the match as Ryan Coldclough’s rasping free-kick put them ahead.
Barnsley responded instantly via Alfie Mawson and despite controlling proceedings for much of the encounter, were unable to put Crewe to the sword, allowing the visitors to steal an unlikely win.
Barnsley started the match on the front foot and saw chances from Kadeem Harris and Marley Watkins well kept out by a busy Ben Garratt.
However the visitors nicked the opener against the run when Marley Watkins conceded a free kick in a dangerous position. Coldclough fired in an unstoppable effort from 20 yards which silenced Oakwell.
But the ground was soon bouncing after the Reds netted an instant reply as skipper Mawson headed home the equaliser a minute later.
Despite dominating play for long spells of the first half, the visitors’ goal remained largely untroubled but Garratt had to react fast again early in the second half to deny Conor Hourihane’s low strike.
Then on the hour mark, Sam Winnall burst through on a tenacious run before pulling the ball back across the six yard line but Watkins couldn’t quite stretch far enough to turn the ball home.
Crewe pinched their winner 11 minutes from time with a rare foray into the host’s half. Adam King burst down the right wing before crossing and Dalla Valle chested the ball home at the front post.
Barnsley almost nicked a point in stoppage time when Hourihane’s free kick from out wide was headed goalwards by Mawson but Garratt produced a top-drawer save to tip the ball over the bar.
Then Pearson sent in an excellent cross which was headed on by Winnall but Garratt made another outstanding save to deny the striker.
Barnsley FC: Townsend, Wabara, Mawson, Nyatanga, G. Smith, Watkins, Scowen, Pearson, Hourihane, Harris (M. Smith 80), Winnall.
Subs: Davies, Bree, Roberts, Rothwell, Digby, White.
Crewe Alexandra: Garratt, Baillie, Nugent, Guthrie, Turton, Inman, Atkinson, Fox, Colclough, King, Della Valle.
Subs: Nizic, Cooper, Saunders, Jones, Wintle, Ainley, Mullarkey.