Paul Caddis was the unlikely scoring hero as Blues blew away Barnsley with a ruthless first-half performance.
Right-back Caddis scored his first goal for the club with an unstoppable effort in the 13th minute before doubling his tally from the spot in the 22nd, after Nikola Zigic had been brought down in the six-yard box.
Zigic then get in on the act with a delightful chip over ex-Blues goalkeeper Jack Butland to wrap this encounter up as early as the 37th minute. It was Blues' second successive win on the road and Lee Clark's side have now claimed seven of the last nine available points in the Sky Bet Championship.
After a scrappy start, it was Blues who carved out the first chance of the match in the fifth minute. Callum Reilly intercepted the ball 25 yards out and had time and space to shoot but instead opted to play in Zigic who had his shot blocked in the area.
Then came Caddis' moment of magic. The Scotland international pounced on a loose ball in the middle of the park, skipped past a challenge and sent a stunning low drive into the bottom right hand corner, well beyond the reach of the out-stretched Jack Butland.
Within eight minutes, Caddis was putting the ball down on the penalty spot and looking to claim a brace for the first time in his career. From Shane Ferguson's right-side corner, Zigic was grappled to the ground in the six-yard box and referee Kevin Wright pointed to the spot.
Caddis made no mistake; sending Butland the wrong way by finding the bottom right corner.
Blues understandably had the wind in their sails and Tom Adeyemi burst forward in the 33rd minute to be played in by Jesse Lingard down the right-side of the area but his shot was blocked out for a corner that came to nothing.
The majority of the Oakwell crowd were left shell-shocked eight minutes before the interval when Zigic started and finished a fine move for Blues' third. The Serbia international headed clear a Barnsley free-kick at one end, Caddis raced down the right and played a ball inside for the big man. After some dithering on the ball by Jim O'Brien, Zigic burst clear and lofted a delightful effort over the onrushing Butland.
The Tykes, who made two changes at the break, desperately tried to muscle their way back into this one but Blues held firm. Barnsley did, however, have the ball in the net in the 64th minute when Marcus Pedersen flicked home Tom Kennedy's drive from the left but the effort was ruled out for offside.
Darren Randolph had to be alert in the 71st minute when Barnsley sub Jason Scotland teed up Stephen Dawson on the edge of the area but the Irish 'keeper gathered his low shot.
Blues did have their chances to further extend their healthy lead. Successive Lingard shots, the first blocked and the second wide, came in the 72nd minute, while the lively Manchester United loanee was on the receiving end of a smart pass from Aaron Mclean in the 82nd minute only to see Butland make the save.
Prior to Mclean's arrival for Zigic in the 75th minute, Wade Elliott was introduced for Shane Ferguson in the 68th minute to register his 100th appearance for the club.