"You could see the pain when he came off at full-time but that will subside tonight when he realises he's scored his first hat-trick for many years here," Warnock said.

"The thing about Ralls is he's the easiest player to criticise from the fans, but he never hides, he always wants the ball even when he's not having a good time.

"It takes a lot of courage to play like he does so it's all credit to him when he has a day like today. I hope he really enjoys the weekend.

"It is one of the best wins since I have been at the club, under the circumstances. You could see how nervous the players were.

"We had to put a performance on for the fans and we did. They stayed and saluted us even though they must have been wet through.

"They knew how bad they were at Swansea. The only way to get the fans back in favour was to show how much it means to us and we did that."

A Bluebirds victory looked unlikely after Kristian Pedersen bundled in the opener for the dominant Blues after Lukas Jutkiewicz's header across goal on 17 minutes.

But a harsh penalty decision turned the game on its head.

Andrew Madley judged Birmingham skipper Harlee Dean to have tugged on Aden Flint's shirt at a corner.

Ralls stepped up and found the bottom right corner to draw the Bluebirds level and they competed the comeback 10 minutes later when Curtis Nelson scrambled the ball home for his first Bluebirds goal.

Danny Ward's dangerous tackle on Kerim Mrabti earned him a straight red card and opened the door for Pep Clotet's men.

But despite being down to 10 men, Nathaniel Mendez-Laing pushed forward and outmuscled Pedersen before squaring the ball for Ralls to sweep the ball into the net.

Ivan Sunjic gave the travelling Blues fans hope when he picked up the ball 25 yards out and fired a thunderbolt into the top corner.

But the optimism evaporated deep into injury time when captain Dean was the second man to be shown a straight red after elbowing Ralls in an aerial duel that sparked a skirmish.

Birmingham were unable to build on their back-to-back victories, but interim head coach Clotet believes their performance deserved more.

"It was a game with a lot of emotion and intensity and we feel we leave Cardiff without receiving what we deserve," he said.

"The difference between both teams was that Cardiff had all the luck when it came to turning chances into goals and we didn't.

"We knew it would be a very tough place to come to and a very difficult opponent because it's very easy to get sucked in to Cardiff's football. But we started playing very well and created a lot of chances.

"We had 25 shots on goal and we still only managed to score two goals. We must understand how to put the game to bed as soon as we can.

"As soon as Cardiff had an opportunity to get back into the game, they took it and that was the difference.

"It was hard work because we had to build a lot to make the chances and we weren't lucky enough to take them."