Troy Deeney was denied by the crossbar as Birmingham were forced to settle for a point from a goalless draw at home to Preston.
Birmingham went close in the sixth minutes when Dion Sanderson whipped in an inviting cross and Deeney's diving header rattled the bar.
But the Blues could not build on their bright start with Preston eventually claiming a fourth straight draw in the league.
A clean sheet, at least, was welcome for Lee Bowyer's men. They had conceded only three goals in their opening six games but then let in seven in their previous two defeats against Peterborough and Fulham.
Preston went into the game unbeaten in their last five league games and they moved into the fourth round of Carabao Cup with a 4-1 midweek win over Cheltenham.
Blues keeper Matija Sarkic saw an early clearance charged down by Sean Maguire, with the ball looping just over the bar and then Josh Earl, making his 50th Preston appearance, saw an effort pushed wide.
It was a frantic start and, after Deeney's effort, Blues went close again on 12 minutes as Tahith Chong forced Daniel Iversen into a save.
After an initial glut of chances, clear openings became less frequent although Sepp Van den Berg saw a low shot comfortably taken by Sarkic on 21 minutes while the Blues keeper had to be alert to deny Emil Riis Jakobsen.
Harlee Dean blazed over at the other end after meeting a free-kick at the far post but the sides went into the break all square.
Preston received a huge let off just four minutes into the second half as Ben Whiteman cleared off the line as Jeremie Bela's low cross struck Andrew Hughes. From the follow up, Iversen did well to parry away Maxime Colin's goal-bound strike.
Bowyer made a double attacking change in a bid to find a way through the visiting defence, throwing on Lukas Jutkiewicz and Chuks Aneke for Deeney and Scott Hogan on 67 minutes.
Preston responded by bringing on Alistair McCann and Josh Murphy for Whiteman and Maguire.
But, if the substitutions were meant to inject some threat into the final stages, they failed to pay off with neither side able to find the all important winner.
