Barnsley lost 2-0 at home to Championship leaders Brighton and Hove Albion on Saturday.
Sam Baldock's second half brace did the damage for the table-toppers and left the Reds in ninth, nine points off the play-offs. Barnsley several chances but Brighton were more clinical and worthy winners at Oakwell.
Paul Heckingbottom made just one change from the side that won at Aston Villa on Tuesday, with Gethin Jones replacing fellow loanee Callum Elder at left-back.
After Brighton's Baldock was booked for diving in the home box, Barnsley thought they should have had a penalty when Lewis Dunk appeared to handle the ball in the area but the referee gave nothing.
The Seagulls had the first real chance of the game when Jamie Murphy headed Bruno's cross over the bar from close range in the 19th minute.
Marley Watkins nearly put the hosts in front with a vicious low shot from 25 yards which was very well kept out of the bottom left corner by a full-stretch David Stockdale, who then caught a more central shot from Adam Armstrong after the striker had cut in from the left wing.
Baldock fired a shot just wide from long range then Reds captain Marc Roberts headed Ryan Kent's corner narrowly off target.
Former Sheffield United man Murphy came close a minute into the second half when he powered down the left wing into the box but fired into the side netting. Tom Bradshaw had a good chance for Barnsley but fired wide of the near post on the right side of the penalty area.
It was the visitors who took the lead when Baldock smashed a magnificent volley over Adam Davies from the edge of the box after the ball sat up perfectly for him. Knockaert almost made it 2-0 when he ran past several home players but fired straight at Davies.
Barnsley had a golden chance to level when Ryan Kent ran onto a good pass by Watkins and pulled the ball back to substitute Adam Hammill who blazed over the bar from then yards out. It was 2-0 soon after when Hammill lost the ball and Knockaert produced another superb run down the right wing followed by a low cross which was turned in by Baldock.
Watkins could have pulled one back but he headed Hammill's cross straight at David Stockdale, who denied him with a far better save moments later he dived down to his right to stop the shot from the right of the box then Andy Yiadom's follow-up effort was blocked.
Armstrong and Hammill both narrowly missed the target from long-range but the Reds were beaten.
