"Opposing players would pick up on that. Players will study you and see what you do.

"He's recognising that – recognising where he can get on the ball, where he can half-turn and hurt the opposition.

"Then it's about trusting your technique and honing that technique, which he does every day when he trains.

"I'm pleased for him. He's got international football, so a lot on his plate to deal with, but I think you're seeing a player get better and better."

Rangers lost their previous three Championship matches and have been defensively vulnerable, but this time they stood firm – albeit with help from an appalling early miss by Tahith Chong.

Warburton admitted: "It was good to keep a clean sheet. Teams will look at us and say 'They'll score one or two but they're vulnerable'. We can't be vulnerable.

"It was almost like they expected us to score but were going to give it a go themselves and see if they could expose us.

"We stood up against a physical approach and dealt with that. We looked more solid and more cohesive."

Birmingham boss Lee Bowyer bemoaned the miss by Chong when the match was goalless.

Troy Deeney nodded Jeremie Bela's cross back towards the on-loan Manchester United youngster, who misdirected his header into the arms of keeper Seny Dieng. It was the Blues' only effort on target.

Rangers had another let-off before taking the lead when Deeney was unable to get to Ivan Sunjic's low cross.

"We had two massive opportunities to score and then they get the goal," said Bowyer.

"We started really brightly and caused them problems, asked questions of them and didn't take the chances when they came.

"The only difference on the night was Chair, who was clinical in front of goal and caused us problems. But I think if we score one of those two chances then it is a different game.

"We have to be more clinical in front of goal. It's another chance we've missed from inside the six-yard box.

"It concerns me because we work hard at finishing. To have one on target – that's been our problem.

"That stat is not good enough. We had opportunities and asked questions of a good team – and we were away from home.

"Before their second goal we were also causing them problems. Then we switched off at the back and they scored again."