Chris McCann scored at both ends of the pitch to inadvertently gift Barnsley a Boxing Day victory at Burnley.
A superb strike from Jamie Cureton, scoring his first goal for the Tykes from the edge of the area, gave Barnsley the lead after six minutes.
Burnley midfielder McCann converted Robbie Blake's cross to equalise seven minutes before the break.
But McCann went from hero to villain in the 67th minute when he steered a Jamal Campbell-Ryce cross into his own net.
Burnley boss Owen Coyle:
"If you analyse the 95 minutes we were the better team without getting to the standards we have set previously.
"We like to play a high tempo and missed a couple of gilt-edged chances. But we will take our medicine and come back.
"They had a game plan which went perfectly for them and meant we were chasing the game."
Barnsley boss Simon Davey: "It was a great result and we have done the double over them when they have got to the semi-final of a cup and are in the top four.
"I said to the players before the game that we are the only team to beat them in recent weeks and that includes Chelsea and Arsenal.
"We deserved it. You have to take the chances when they come and we did."
Burnley: Jensen, Duff, Carlisle (McDonald 78), Caldwell, Jordan, Elliott, Alexander, McCann, Eagles, Paterson, Blake (Thompson 65).
Subs Not Used: Penny, Gudjonsson, Mahon.
Booked: Jordan.
Goals: McCann 38.
Barnsley: Muller, Van Homoet, Foster, Moore, Kozluk, Campbell-Ryce, Hassell, De Silva, Leon (Colace 58), Cureton (Odejayi 82), Macken (Rigters 72).
Subs Not Used: El Haimour, Guedes.
Booked: Moore.
Goals: Cureton 6, McCann 67 og.
Att: 16,580.
Ref: Scott Mathieson (Cheshire).
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