Barnsley threw away the lead at Southend and fell to a third straight League One defeat.
Josh Scowen's penalty had put the Reds in front at Roots Hall but strikes from Anthony Wordsworth and Luke Prosser handed Southend United the three points.
Lee Johnson opted to play a 5-3-2 formation again with Michael Smith favoured for Sam Winnall.
Dan Crowley, back from international duty with England under 19s, had an early goal ruled out for offside.
Wordsworth then slipped by Lewin Nyatanga but Adam Davies turned his shot behind for a corner.
Myles Weston also had two efforts on goal in the early stages.
Barnsley got the opener on 24 minutes. Marley Watkins beat Southend 'keeper Dan Bentley to a long ball. Bentley then clattered into Watkins and referee Charles Breakspear awarded a spot kick.
The home fans seemed to think the foul had been committed outside of the box but the referee showed no hesitation.
Scowen sent the booked Bentley the wrong way from the spot.
The hosts were still to go in at the break ahead. It was Wordsworth who got them level when he bent in a shot from the edge of the box on 36 minutes.
Just seven minutes later they went in front when Weston's cross found its way to the back stick and defender Prosser bundled in.
Barnsley brought on Winnall and Simeon Jackson in the second period in a bid to get something from the game.
Jackson was the first to get a sight of goal but Southend skipper John White blocked his shot.
A misplaced Crowley cross then concerned Bentley for a second but it drifted wide.
It was the home side who looked the more likely to get the fourth goal of the game.
Weston threatened regularly and Ben Coker sliced a shot wide from 25 yards.
The Reds' best chance of getting a leveller was through Winnall but his flicked header was cleared on its way to goal.
Barnsley: Davies, Wabara (Harris 73), Mawson, Nyatanga, Roberts, G Smith, Scowen, Pearson, Crowley, Watkins (Winnall 48), M Smith (Jackson 65). Unused subs: Townsend, Digby, Bree, White.
Attendance: 6,572 (487 from Barnsley)
