Carlton Morris and Alex Mowatt inflicted a third successive defeat on Blackburn after inspiring Barnsley to a 2-1 triumph at Oakwell.
Substitute Morris broke the deadlock in the 72nd minute, meaning the former Shrewsbury and MK Dons striker has now scored in back-to-back games for the first time since October 2017.
Mowatt then doubled the advantage in the final minute, rendering Adam Armstrong's stoppage-time reply - his 20th goal of the season - a mere consolation as the Reds followed up their win over Brentford.
Barnsley threatened most during the opening exchanges with Conor Chaplin's stinging 25-yard shot pushed into the air by Blackburn's Thomas Kaminski.
After a stretching Sam Gallagher failed to latch on to Elliott Bennett's through-ball with home keeper Brad Collins stranded out of his goal, Cauley Woodrow then headed over from close to the penalty spot following Callum Styles' corner at the other end.
An edge-of-the-box Romal Palmer volley also bounced narrowly wide for the Tykes before Victor Adeboyejo charged on to a quickly-taken Chaplin free-kick through the left channel only for Kaminski to direct his eight-yard side-footed effort on to the crossbar and over.
Blackburn managed their first attempt of the night after 36 minutes but Darragh Lenihan's header from Stewart Downing's bending right-wing cross lacked the venom and direction to trouble Collins.
Bradley Dack went closer for Tony Mowbray's men on the stroke of half-time when he headed just over from Barry Douglas' left-wing delivery.
After his side made a lethargic start to the second period, Barnsley boss Valerien Ismael responded with a triple substitution in the 55th minute having already replaced Styles with Jordan Williams at the interval.
Morris made an instant impression and was only denied a goal from his first contribution by a superb block from Taylor Harwood-Bellis.
Moments later, Mowatt dragged a 20-yard opportunity wide, while Gallagher's header was too weak to trouble Collins for Rovers just past the hour.
Midway through the half, Kaminski unconvincingly shovelled away Mads Andersen's header from a Mowatt free-kick.
Fellow defender Michal Helik, meanwhile, headed woefully off target following Callum Brittain's inviting right-wing delivery before Morris intervened.
Picking the ball up in the left channel, the 25-year-old striker cut inside and pinged a powerful diagonal strike in off a helpless Kaminski's far post from the edge of the penalty box.
Brimming with confidence, he almost grabbed a second but Kaminski was equal to his 12-yard drive.
Mowatt was then sent clear by Daryl Dike and calmly rounded the Blackburn keeper before rolling the ball into an unguarded net.
Armstrong, who had not had a sniff all night, pulled a goal back with one of the last kicks of the game, latching on to a long punt forward in the fourth minute of added time and lifting the ball from 25 yards over Collins, who was caught well off his line.
What the managers said...
Barnsley's Valerien Ismael: "I know that with the schedule and squad depth we have now, we have more possibility to do something with our bench after the work we put in during the transfer window. The first half was pretty evenly balanced in terms of the chances for both teams, but I knew the bench could win us the game and I wanted us to stay in it and then apply more and more pressure.
"Playing Chelsea and Brentford last week took a lot of energy out of us and there was a big impact from all five players who came on. I'm delighted about the substitute rule this season because it gives you more options to have an impact on the game and we scored at the right moment.
"At 1-0, we then had a lot of chances to finish the job but we were a bit sloppy with the final pass before Alex finally scored. We went on to concede a goal completely unnecessarily, but it wasn't a big deal as we won, got the points, moved up the table again and carried on our momentum. We're on 42 points now and need eight more to reach our first target this season."
Blackburn's Tony Mowbray: "I want to get between 70 and 75 points, but Blackburn Rovers haven't been tearing up this division to get in the Premier League for a lot of years and we're not alone in that respect. Inconsistency is there for a lot of teams in this division. There's only really Brentford who have put together a fantastic run this season. I'm sure there's an unbeaten run around the corner for us and we'll have to go on a couple if we are to make the play-offs.
"This game was what we expected from Barnsley and one that supporters will probably be happy that they missed, because it was not much of a spectacle. There was a lot of long balls and they are a very direct team who press extremely well from the front. We tried to nullify Barnsley's strengths but did not have the ability to deal with them and fell down on the basics in terms of the goals we conceded."