Nikola Zigic salvaged a stoppage-time point for Birmingham thanks to Tomasz Kuszczak's howler as Brighton's play-off aspirations suffered a blow.
It was the third time this season the Serb has rescued a point, as Kuszczak let the ball through his hands.
Steven Caldwell headed the hosts in front but the Seagulls levelled courtesy of Ashley Barnes' strike.
David Lopez volleyed what looked to be the winner before half-time only for Zigic to equalise late on.
Even then, Brighton could have nicked it, but Blues' sought-after goalkeeper Jack Butland produced a wonder save to keep out Dean Hammond.
Brighton will feel like it is two points dropped having looked set for their first win over Birmingham in eight attempts since 1989 and only their second ever success at St Andrew's.
- Wayne Bridge made his 400th club career start
And the visitors' late set-back has seen them drop five points behind the top six, despite moving up one place in the Championship table to eighth.
Cash-strapped Blues have just one win in their last 10 games and they remain in 20th spot - five points clear of the relegation zone.
Following a tentative start an unmarked Caldwell met Rob Hall's corner after 18 minutes to power a header past Kuszczak.
Yet the visitors levelled in the 24th minute. Andrea Orlandi broke down the left and cut a ball back for Barnes who fired into the bottom corner from 20 yards.
Chris Burke, who netted the winner a 1-0 triumph for Birmingham in the reverse fixture earlier this season, was thwarted by a fine parried save from Kuszczak just before half-time.
And the stop proved crucial as Brighton claimed the lead in the 43rd minute with Wayne Bridge sending over a great cross to Lopez, who volleyed under Butland.
Zigic came on at half-time and the giant striker looped a header over before he sealed an unlikely point.
Live Text Commentary
Full Time The referee signals the end of the game.90:00 +4:03
The referee blows for offside. Free kick taken by Jack Butland.90:00 +2:36
Rodriguez Vicente decides to take the corner short.90:00 +1:01
The assist for the goal came from Marlon King.90:00 +1:01 Goal scored
Goal! - Nikola Zigic - Birmingham 2 - 2 Brighton Nikola Zigic finds the net with a headed goal from close in. Birmingham 2-2 Brighton.90:00 +1:00
Marlon King crosses the ball,87:14
Paul Caddis crosses the ball, save made by Tomasz Kuszczak.85:56
Christopher Burke delivers the ball, Adam El-Abd makes a clearance.85:16
The referee blows for offside. Jack Butland takes the free kick.84:44
Paul Robinson challenges Rodriguez Vicente unfairly and gives away a free kick. Direct free kick taken by Liam Bridcutt.82:14
Effort on goal by Dean Hammond from long range goes harmlessly over the target.81:05 Substitution
Substitution Rodriguez Vicente comes on in place of Craig Mackail-Smith.81:05 Substitution
Substitution Ravel Morrison replaces Callum Reilly.79:17
Paul Caddis crosses the ball, Headed effort from the edge of the area by Nikola Zigic goes wide of the right-hand upright.77:13
Robert Hall takes a shot. Blocked by Dean Hammond. Corner taken by Robert Hall, save made by Tomasz Kuszczak.76:54
The ball is delivered by Paul Caddis, clearance made by Dean Hammond.75:51 Substitution
Substitution Gary Dicker comes on in place of Andrea Orlandi.75:02
Long range shot by Christopher Burke goes wide right of the net.73:53
Paul Robinson restarts play with the free kick.73:53 Booking
Booking Adam El-Abd is given a yellow card.
Free kick awarded for a foul by Adam El-Abd on Marlon King.72:19
Ashley Barnes takes a shot from just outside the penalty area which clears the crossbar.70:28
Outswinging corner taken by Andrea Orlandi.68:57 Substitution
Substitution Will Buckley replaces Moreno David Lopez.68:57 Substitution
Substitution Marlon King on for Nathan Redmond.68:57
Centre by Nathan Redmond.67:50
The ball is delivered by Christopher Burke, Adam El-Abd makes a clearance.66:33
Free kick taken by Robert Hall.66:33 Booking
Booking The referee shows Gordon Greer a yellow card.66:27
Gordon Greer gives away a free kick for an unfair challenge on Robert Hall.65:37
Morgaro Gomis concedes a free kick for a foul on Craig Mackail-Smith. Direct free kick taken by Adam El-Abd.65:20
Christopher Burke produces a cross, clearance made by Adam El-Abd.61:41
A cross is delivered by Paul Caddis.59:30
Strike on goal comes in from Andrea Orlandi from the free kick, Jack Butland makes a save. Outswinging corner taken from the right by-line by Moreno David Lopez.59:30 Booking
Booking Steven Caldwell goes into the book for unsporting behaviour.59:19
Ashley Barnes fouled by Steven Caldwell, the ref awards a free kick.58:39
Corner taken right-footed by Moreno David Lopez from the right by-line, Steven Caldwell makes a clearance.57:59
Andrea Orlandi takes a shot. Callum Reilly gets a block in. Outswinging corner taken by Andrea Orlandi from the left by-line played to the near post.55:36
Centre by Craig Mackail-Smith, clearance made by Curtis Davies. Outswinging corner taken by Andrea Orlandi from the right by-line.54:55
Outswinging corner taken by Robert Hall, Wayne Bridge manages to make a clearance.53:51
Foul by Nikola Zigic on Dean Hammond, free kick awarded. Direct free kick taken by Gordon Greer.52:08
Robert Hall crosses the ball in from the free kick, clearance made by Moreno David Lopez.52:08 Booking
Booking Booking for Inigo Calderon for unsporting behaviour.52:03
Free kick awarded for a foul by Inigo Calderon on Robert Hall.49:09
A cross is delivered by Christopher Burke, clearance by Adam El-Abd. Robert Hall decides to take a short corner. The ball is delivered by Christopher Burke, Tomasz Kuszczak makes a comfortable save.48:17
Ashley Barnes is flagged offside by the assistant referee. Jack Butland takes the free kick.45:52
Free kick awarded for a foul by Nikola Zigic on Tomasz Kuszczak. Free kick taken by Tomasz Kuszczak.45:28
Corner taken by Robert Hall, Tomasz Kuszczak makes a save.45:01
The match restarts for the second half.45:01 Substitution
Substitution Wade Elliott goes off and Nikola Zigic comes on.45:00 +2:05 Half time
Half Time The referee blows for half time.45:00 +1:32
Handball by Dean Hammond. Callum Reilly restarts play with the free kick.45:00 +0:42
The ball is swung over by Wayne Bridge, Jack Butland makes a save.44:37
Foul by Wade Elliott on Dean Hammond, free kick awarded. Gordon Greer takes the free kick.44:09
Ashley Barnes has an effort at goal from just inside the box that misses to the left of the target.42:53
Wayne Bridge provided the assist for the goal.42:53 Goal scored
Goal! - Moreno David Lopez - Birmingham 1 - 2 Brighton Moreno David Lopez finds the net with a goal from inside the penalty area to the top left corner of the goal. Birmingham 1-2 Brighton.39:56
Shot by Christopher Burke. Tomasz Kuszczak makes a save. Corner taken by Robert Hall from the left by-line, clearance made by Adam El-Abd.38:59
The ball is crossed by Robert Hall, Adam El-Abd makes a clearance.37:19
Craig Mackail-Smith gives away a free kick for an unfair challenge on Curtis Davies. Jack Butland restarts play with the free kick.34:46
Shot from long range by Nathan Redmond goes wide of the left-hand upright.34:08
The ball is sent over by Ashley Barnes, Morgaro Gomis manages to make a clearance.33:33
Nathan Redmond takes a shot. Save made by Tomasz Kuszczak.32:20
Free kick awarded for an unfair challenge on Morgaro Gomis by Dean Hammond. Morgaro Gomis takes the direct free kick.30:48
Steven Caldwell gives away a free kick for an unfair challenge on Ashley Barnes. Andrea Orlandi crosses the ball in from the free kick.30:14
The ball is crossed by Wayne Bridge, Paul Robinson makes a clearance.29:08
Effort on goal by Callum Reilly from long distance goes over the crossbar.27:07
Corner taken by Andrea Orlandi from the right by-line to the near post, save by Jack Butland.25:55
Free kick awarded for a foul by Steven Caldwell on Andrea Orlandi. Strike on goal comes in from Moreno David Lopez from the free kick.25:26
Craig Mackail-Smith challenges Jack Butland unfairly and gives away a free kick. Jack Butland restarts play with the free kick.23:15
The assist for the goal came from Andrea Orlandi.23:15 Goal scored
Goal! - Ashley Barnes - Birmingham 1 - 1 Brighton Ashley Barnes finds the back of the net with a goal from just outside the penalty box to the bottom left corner of the goal. Birmingham 1-1 Brighton.23:15
The ball is sent over by Andrea Orlandi,22:21
The ball is delivered by Craig Mackail-Smith, Curtis Davies makes a clearance.18:39
Moreno David Lopez takes the outswinging corner, Liam Bridcutt produces a right-footed shot from just outside the box that goes wide right of the goal.17:13
Robert Hall provided the assist for the goal.17:13 Goal scored
Goal! - Steven Caldwell - Birmingham 1 - 0 Brighton Goal scored by Steven Caldwell from close range to the top left corner of the goal. Birmingham 1-0 Brighton.16:43
Inswinging corner taken left-footed by Robert Hall,15:45
The assistant referee flags for offside against Moreno David Lopez. Jack Butland restarts play with the free kick.13:06
Direct free kick taken by Jack Butland.13:06 Booking
Booking The referee cautions Liam Bridcutt for unsporting behaviour.12:46
Free kick awarded for a foul by Liam Bridcutt on Morgaro Gomis.11:38
Christopher Burke produces a curled left-footed shot from deep inside the area which goes wide of the left-hand post.11:00
The ball is swung over by Ashley Barnes.10:05
Nathan Redmond concedes a free kick for a foul on Adam El-Abd. Free kick taken by Adam El-Abd.9:27
The ball is swung over by Robert Hall, Tomasz Kuszczak makes a save.7:53
Free kick awarded for an unfair challenge on Robert Hall by Adam El-Abd. Direct effort from the free kick comes in from Robert Hall, blocked by Ashley Barnes. Short corner taken by Robert Hall.7:14
Morgaro Gomis crosses the ball, blocked by Craig Mackail-Smith.4:11
The ball is delivered by Paul Caddis.3:59
The ball is swung over by Craig Mackail-Smith, save by Jack Butland.1:35
Unfair challenge on Inigo Calderon by Robert Hall results in a free kick. Free kick taken by Gordon Greer.0:00
The game kicks-off.
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