It's another terrific result for the Reds as second half Chaplin and Brown goals see Barnsley overcome Blackburn at Oakwell.
Head Coach, Gerhard Struber had made just the one change from Saturday's draw with Millwall, bringing Jordan Williams in at right wing-back in place of Kilian Ludewig.
It was a very bright start for the hosts, as Cauley Woodrow twice tested away 'keeper Christian Walton from around the edge of the box, the second effort stinging the Rovers' goalies hands.
Romal Palmer struck over the bar after a flowing Reds move, ably set up by Jacob Brown as Struber's men took the initiative.
The best Barnsley move came on 20 minutes as Alex Mowatt got himself into the box, and onto Elliot Simoes' through-ball, but the skipper's shot from 10 yards was spooned out via a deflection off an outstretched leg of a defender.
After a drinks break, it was practically all Blackburn as former Reds loanee Adam Armstrong began to cause the backline all kinds of trouble with his pace.
He first tested Jack Walton with a tame effort having seen off Michael Sollbauer, before again getting beyond his man and into the box only to see a rasping low drive turned behind by Walton.
On the half hour, a real heroic clearance from Brown as he was on hand to hook away from the line after Bradley Johnson's header was only parried by Walton following a superb Stewart Downing corner kick.
It was all Rovers for a 10 minute spell prior to the break. A spell which saw the end of Palmer, injured, and replaced by Callum Styles.
But it was Barnsley who finished the half strongest, as Mowatt again was denied by the away stopper when he fired in an effort from the edge of the box.
HALF TIME: Reds 0-0 Rovers
The game turned on 48 minutes, as Dominic Samuel somehow contrived to place a shot over when free at the back post, meeting Downing's delightful free-kick. It was a huge chance.
Struber rang the changes soon after, with Ludewig, Luke Thomas and Conor Chaplin coming on in place of Simoes, Jordan Williams and Marcel Ritzmaier.
The changes had the desired effect as just three minutes later, a stupendous deep cross from the right, put over by Ludewig was met perfectly in the air by Chaplin who powered in his header to give the Reds the lead.
There were more chances created for Thomas, Mowatt and Brown before Rovers saw substitute Ben Brereton sent off for kicking out at Ludewig who'd beaten him with skill down the line.
On 77 minutes, the Reds doubled their lead. A fine interception from the impressive Styles, a through-ball from Mowatt and Brown skipped into the box to finish low beyond the onrushing 'keeper.
It's seven points from nine since the return to play as the Reds continue to fight for their Championship lives.
FULL TIME: Reds 2-0 Rovers
Walton, J.Williams (Ludewig), Sollbauer, Andersen, B.Williams, Ritzmaier (Styles), Palmer (Thomas), Mowatt, Brown, Woodrow (Schmidt).