Birmingham head coach Aitor Karanka wants his side to show a nasty streak after they surrendered the lead and lost 2-1 at home to Barnsley.
Blues led the Sky Bet Championship contest through Scott Hogan's goal, only for Cauley Woodrow (penalty) and Callum Styles to turn the game on its head and make it six games without a win for Karanka's team.
He said afterwards: "They were more aggressive than us and again it is something we have to analyse. They had more energy than us and it is something we have to correct.
"Sometimes if you argue with a team-mate it is nothing personal and something we have to learn.
"They are very good (well behaved) but we have to demand much more from each other. They are too nice.
"Sometimes you need to be more aggressive. When you are a player and if a team-mate argues with you, it is because he wants the best for you."
Karanka struggled to explain another lacklustre performance from Blues, adding: "It was a frustrating performance, a frustrating game.
"We couldn't pass the ball three or four times in a row in the first half and it was difficult.
"We started the second half much better and the only time we put two or three passes together we scored. I don't understand why we are not doing it more often."
Barnsley head coach Valerien Ismael was delighted with the character of his side after they made it five wins from eight games.
He said: "I am very happy with the start – it gives you a good feeling and improves our standing in the Championship. This win will give us more confidence.
"We told the players before the game they had two tasks: To sustain their performance – and I was delighted with that – and show more mentality and the desire to get the points.
"It was very important to have a game-changer after going one goal down."
Ismael believes Styles, 20, is an excellent prospect after hailing his matchwinning effort.
He continued: "He's a special weapon for us on the edge of the box. He's got a great strike on him.
"Dominik (Frieser) tries to score for us from those throw-ins – he tries this in every game."
Woodrow went from villain to hero and bagged an early birthday present as he paved the way for the Tykes' win.
The striker – who turns 26 on Wednesday – equalised with a penalty in the 71st minute to make up for two first-half misses, before Styles struck from just inside the box on 84.
Hogan's 56th-minute strike ended a run of 326 minutes without a goal in open play for Birmingham, after Jonathan Leko's backheel let in Maxime Colin to cross.
But they conceded a penalty when Kristian Pedersen made contact with Brittain and Woodrow calmly sidefooted to goalkeeper Neil Etheridge's left to equalise from the spot.
Then Styles drilled home the winner after the home side had failed to deal with substitute Frieser's long throw.
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