Gary Birch was the difference between the two sides when leaders Argyle visited Oakwell, as his goal nine minutes from time meant The Pilgrims travel back down to Devon empty handed.
The win keeps The Tykes' slim hopes of a play-off spot well and truly alive.
Second played third at Ashton Gate as Queens Park Rangers went to Bristol City, leading their hosts by three points.
However, by the end of the day that gap was erased as Christian Roberts' strike five minutes before the break was enough for The Robins to grab three points.
Bournemouth left it late to grab a point at home to Colchester as James Hayter's 86th-minute strike cancelled out Greg Halford's opener.
Brentford also had to come from behind to draw at home to Chesterfield, but both sides left it even later as both Stephen Evans and Ian Evatt struck in the 90th minute to hand each side a point.
Brighton made no mistake at home to Hartlepool as Leon Knight and Chris Iwelumo gave them a 2-0 win, while Grimsby followed suit by handing Sheffield Wednesday another disappointing defeat at Blundell Park thanks to Darren Mansaram and Anthony Crane goals.
Dean Crowe gave Oldham the lead away at Luton Town but the lead lasted just a minute as Enoch Showunmi levelled for The Hatters.
Notts County gave Blackpool a 4-1 hammering at Meadow Lane, with two goals from Paul Heffernan and goals from Anthony Scully and Steve Scoffham making Mike Sheron's goal academic.
Peterborough thumped Swindon 4-2 at London Road with Adam Newton, David Farrell, Richard Logan and Steve Thomson all on target and Matty Heywood and Sam Parkin replying for the visitors.
Two goals from Richard Lambert, one a penalty, gave Stockport County a 2-1 win over Rushden & Diamonds - who scored through Barry Hunter.
Ian Sharps gave Tranmere a 1-0 win at Wrexham while Darren Currie's brace gave Wycombe a 2-1 win over Port Vale, who had taken the lead through Stephen McPhee.
