An own goal by Curtis Davies earned Blackpool a narrow first-leg lead over Birmingham in an absorbing Championship play-off semi final at Bloomfield Road.
Davies watched in horror as Tom Ince's long-range attempt cannoned off him and flew into the net past Colin Doyle.
The impressive Stephen Dobbie spurned a fine chance to double the lead as Blackpool dominated the second half.
Marlon King grazed the post for Blues, who otherwise offered little and will be relieved to trail by only one goal.
Yet for all their impressive attacking play, Blackpool still have much work to do in next Wednesday's second leg if they are to book a Wembley date.
The tie is still in the balance and Birmingham will be confident of turning the tie on its head in the return at St Andrew's.
It could have been an even better night for the Tangerines when, on 76 minutes, the evergreen Kevin Phillips sent the raucous home crowd - not to mention boss Ian Holloway - wild within moments of stepping off the bench.
In trademark fashion, the former Blues striker stole a march on his marker to head home Matt Phillips's fine right-wing cross. But as he wheeled away in celebration the linesman's flag went up.
Despite the look of anguish on Holloway's face, replays proved the assistant referee's decision to have been the right one.
Both teams are looking to make a quickfire return to the Premier League after being relegated together on the final day of last season with 39 points - a tally that would have all but guaranteed top-flight safety this term.
Blackpool finished one point and one place behind Birmingham in the Championship table, and there was little to choose between them in a thrilling first half.
Visiting keeper Doyle caused his manager Chris Hughton a few worries early on when he hurt his right shoulder colliding with a post while keeping out Ian Evatt's powerful header.
He continued after treatment but the Irishman appeared in some discomfort for the duration of the game, none more so when Dobbie's 33rd minute effort from distance struck him in the chest.
And Doyle's shoulder problem appeared to restrict his movement when Blackpool broke the deadlock in the 44th minute. Former Liverpool player Tom Ince's 22-yard attempt took a cruel deflection off Davies's foot before creeping through the keeper's legs and into the net.
It was tough on Birmingham, who were showing few signs of fatigue, despite it being the 61st match of their campaign.
King was unfortunate with a 14th minute overhead kick while Nathan Redmond lost his composure when he found himself within sight of goal a minute later, and former Coventry striker King went close from 16 yards five minutes before the break.
But for the finishing, it was easy to see why these two sides had managed 157 Championship goals between them this season.
Blackpool threatened to double their advantage when Barry Ferguson went close against his former club while the tireless Dobbie spurned a glorious chance when firing wide from close range in the 63rd minute after clever work by Ince.
The visitors created little after the interval although King went agonisingly close in the dying moments when he clipped the left-hand post after finding himself with time and space inside the Blackpool penalty area.