Blackpool beat Birmingham 1-0 in the first leg of their Championship play-off semi-final on Friday night.
The only goal of the game at Bloomfield Road came just before the break when Thomas Ince's strike deflected off Curtis Davies and ended in the visitors' net.
Blackpool will take their slender advantage to St Andrews next Wednesday for the second leg.
Nathan Redmond and Marlon King might have put Birmingham ahead before Ince's opener, but Chris Hughton's side were forced onto the back foot in the second half, with former Liverpool youngster Ince to the fore.
Stephen Dobbie should have doubled the advantage following a sublime piece of skill from the 20-year-old winger before the Bloomfield Road faithful had hearts in mouths when King clipped the outside of the post in stoppage time.
Blackpool boss Ian Holloway is hoping his die do not regret not winning the game by a wider margin.
"They nearly nicked an equaliser - I'd be fuming if that was the case because, generally, I thought we deserved to just edge it,'' said Holloway, who won the play-offs with Blackpool two years ago.
"I'm delighted it (the goal) went in, I think we needed that, but a couple of those others (Blackpool's chances) - deary, deary me. I hope we don't rue the day that we missed them."
The defeat means Blues lost for the first time in 10 matches and they will now have to end Blackpool's eight-game unbeaten streak if they are to reach the Wembley final on May 19.
Chris Hughton says his side will have to raise their game if they are acheive that aim.
"They were better than us, we'll hold our hand up," he said.
"We'll need be better than we were tonight and if we are that puts us in with a great chance.''