Barnsley's three-game winning run came to an end with a 2-0 loss at Swansea City on Saturday.
The hosts took the lead in the second minute then substitute Victor Adeboyejo scored an own goal midway through the second half.
That meant the Reds slipped down one place to 13th in the table, five points off the play-offs and 13 clear of the bottom three.
It was a disappointing performance from the Reds on a very poor pitch, especially after an even first half when they were second best after the break.
Clarke Oduor replaced the suspended Callum Styles at left wing-back in the only change from the side that beat Preston North End on Tuesday. There were only eight substitutes on the bench with nine allowed.
The Reds conceded after only 75 seconds as, after a free-kick was cleared, a cross was flicked on by Ben Cabango to the unmarked Jamal Lowe who had the whole goal to aim at six yards out and beat Walton. It was the second time in as many games the Reds had conceded in the second minute and the third time in a row they went behind within the first five.
Barnsley responded well and their captain Alex Mowatt saw a 25-yard free-kick pushed away by goalkeeper Freddie Woodman.
The Reds then had a succession of corners, from Oduor and Matty James, and long throws, by Dominik Frieser, but could not carve out a clear-cut opportunity.
There was a nervous moment for the Reds when Walton charged out of his box and fouled Yan Dhanda so received a yellow card as two defenders were covering. Matt Grimes sent the resulting 30-yard free-kick straight at Walton.
The goalkeeper again raced out of his box seven minutes into the second half but perfectly timed his slide tackle on Lowe after a Grimes pass following a poor Chaplin header.
Barnsley made a triple change on 56 minutes with Woodrow, Chaplin and Frieser replaced by Luke Thomas, Adeboyejo and George Miller.
Swansea doubled their lead midway through the second half when Grimes' corner from the right was flicked into his own net by Adeboyejo at his front post.
Adeboyejo could have made amends 13 minutes later when he curled over the ball on the left of the box 15 yards out after Andre Ayew was robbed on the edge of his area by a combination of Miller and Oduor.
At the other end, Jake Bidwell volleyed over a difficult chance from a Jay Fulton cross with six minutes to play.
Swansea (3-4-1-2): Woodman; Cabango, Bennett, Guehi; Roberts, Fulton, Grimes, Bidwell; Dhanda; Ayew, Lowe. Unused: Benda, Latibeaudiere, Manning, Smith, Palmer, Routledge, Cooper, Cullen, Gyokeres. Yellow cards: Roberts. Goals: Lowe 2, Adeboyejo OG 66.
Barnsley (3-4-3): Walton; Sollbauer, Helik, Andersen; Brittain, Mowatt (Kane 82mins), James (Palmer 71m), Oduor; Frieser (Miller 56mins), Woodrow (Adeboyejo 56), Chaplin (Thomas 56mins). Unused: Collins, Moon, Schmidt. Yellow cards: Walton.