Barnsley conceded an injury-time goal a 2-1 Yorkshire derby defeat at local rivals Huddersfield Town on Saturday.
The Reds trailed at half-time but Alfie Mawson levelled two minutes into the second half. Barnsley had chances to win the match in a much-improved display after the break but Terriers substitute Jonathan Hogg netted the last-gasp winner.
Paul Heckingbottom kept the team that beat Derby County and QPR in their previous two matches. Unlike those other games, Barnsley did not dominate the early exchanges with Adam Davies being tested by an Elias Kachunga bicycle kick from close range after Mawson sliced a clearance.
But the Reds soon came into the game with Ryan Kent firing over within the box after a good movie involving Marley Watkins and Adam Hammill. Josh Scowen then headed over when well-placed from a Conor Hourihane corner.
The hosts took the lead on 27 minutes when German left-back Chris Lowe fired into the top right corner after a good passing move.
Heckingbottom made a change at the break with Stefan Payne replacing Tom Bradshaw. The Reds levelled 75 seconds into the second half when Mawson rose highest to head in a long throw from his central defensive partner Marc Roberts.
Kent could have put the Reds in front after a Hammill back-heel and Payne dummy put him through on the left but his shot from 15 yards out was not powerful fought to beat home goalkeeper Danny Ward who dived to his left to save.
There was danger at the other end when Nahki Wells headed Lowe's cross towards the top left corner but Davies made an excellent save to claw it away. Home goalkeeper Danny Ward then produced a full-length dive to keep a 25-yard Kent shot out of the top left corner.
Barnsley were gifted a golden chance to go ahead when Payne ran onto Dean Whitehead's poor back pass to go clean through but hit the outside of the right post.
The Reds were made to pay for that missed chance when Hogg smashed into the top right corner inside the box in the 92nd minute.