Birmingham manager Gary Rowett got just the response he wanted from his players in the second half as they produced a solid display in their 2-0 Sky Bet Championship win at MK Dons.
The Blues remain unbeaten this season and Stephen Gleeson was to put them on their way to this latest win with a superb strike against his old club.
It was the second week in a row in which he had scored after over a year without a goal - but the Dons were annoyed that Birmingham's Demarai Gray was not sent off for pushing Kyle McFadzean.
Rowett said: "I thought it was a good away day performance in the second half because I was actually disappointed with our performance in the first half.
"Our standards have been set so high since I've been here and this season and in the first half I just felt there was a lack of intensity in what we did.
"I just wanted a reaction at half-time and it was probably the angriest that I've been and I threatened to make a couple of changes early in the game if we didn't liven up.
"In the end I made one and I think that change made the difference and we changed the formation - Jacques Maghoma came on the left and we moved Gleeson higher up the pitch.
"I thought by doing that we changed the game and we really dominated the second half in terms of our chances and in terms of our attacking play."
Birmingham broke the deadlock after 57 minutes when Clayton Donaldson pulled the ball back for Gleeson, who clipped a superb effort into the far corner.
The Blues sealed the points with Donaldson again the creator as he slipped through Maghoma and the substitute passed his shot into the net.
MK Dons boss Karl Robinson said: "What Demarai Gray did was violent conduct - people will say 'oh, he's a centre-half who should stay on his feet' but Kyle was caught off-balance.
"I get players sent off for that - I think the kid's a tremendous talent but the referee has got to be brave in his decision.
"I thought the referee allowed people to have a go at him and it affected him.
"We huffed and puffed in the second half and we got into better positions than we have done all season but we don't want to shoot.
"I said to them that I can't take responsibility for their shooting or our mentality after the first goal but I can take responsibility for my poor substitutions.
"Our finishing was poor and with the first chance they get Stephen, who's a wonderful technician, put it in the perfect position - and then we lost our heads."