LOWLY Scunthorpe inflicted the Reds' sixth home loss of the season with a 2-1 win on Saturday.
In what was Danny Wilson's 250th game in charge, Barnsley broke the deadlock in the 29th minute through on-loan Italian hitman Marcello Trotta.
However, their short-lived lead lasted just 60 seconds, with Paddy Madden equalising for Mark Robins' side after good work from Gary McSheffrey.
Madden was at it again in injury time of the first half, scoring what proved to be the decisive goal after cutting the Reds' defence apart with a mazy run.
The defeat is Barnsley's sixth in nine home games going into tomorrow night's South Yorkshire derby clash against Doncaster Rovers.
Wilson said: "Without being too critical, I don't think we played anything like how we can play. I didn't think we had any intensity at all.
"We seemed to get into a lot of trouble by passing the ball too slowly. There wasn't any fluency in our passing."
