Barnsley will be in the League One relegation zone for Christmas following a 2-0 home loss to Wigan Athletic on Saturday.
Wigan took the lead midway through a first half in which they played the better football but Barnsley looked to have a chance of a late equaliser before a defensive mix-up gifted a second on 86 minutes.
The Reds did not move down any places as the sides below them failed to win but they remain in 21st.
Head coach Lee Johnson made on change to his side, dropping captain Alfie Mawson to the bench. Kevin Long returned from suspension to take Mawson's place while Conor Hourihane was given the armband.
After Wigan's Will Grigg and Barnsley's Sam Winnall both headed wide when well-placed, the visitors took a 19th-minute lead following an excellent move. A long ball was headed down well then Michael Jacobs' clever pass put Andy Kellett clean through and he found the top left corner from just inside the box.
Very little happened between the goal and half-time but Wigan had been the better team despite a good first five minutes for the Reds.
In the second half, Hourihane and visiting midfielder Max Power both put long-range shots just wide. Home goalkeeper Adam Davies then denied Kellett a second goal by saving with his legs after the Wigan man was put through one-on-one on the counter-attack.
Ryan Williams came off the bench and impressed, setting up Winnall for two chances but the striker miskicked first one then hesitated with the second and was tackled by ex-Red David Perkins.
The second goal came when Barnsley's defence and goalkeeper hesitated then substitute Yanic Wildschut rounded Davies then fired into the empty net.
Williams netted but the goal was ruled out for offside and Barnsley are now without a home win in six league matches.