Yossi Benayoun's deflected equaliser clinched Champions League football for Liverpool but dealt a massive blow to Birmingham's hopes of Barclays Premier League survival.
Alex McLeish's side had appeared to be coasting to victory after goals from Mikael Forssell and Sebastian Larsson had put them in total command.
But a lethargic Liverpool suddenly came to life and, after Peter Crouch had reduced the arrears, Benayoun's deflected header rescued a point and dealt a massive blow to the home side.
Blues will be wondering how they surrendered two priceless points after appearing to be cruising to only a second win in the last eight matches.
Larsson and James McFadden were a handful throughout for the Reds and Birmingham were also hard to break down - a sharp contrast to the 5-1 mauling at Aston Villa last weekend.
But a failure to keep clean sheets has been an Achilles heel for City all season and they were forced to defend desperately for the final half hour.
Liverpool's inspiration was former Blues winger Jermaine Pennant and he was one of the few players in Rafael Benitez's 'shadow' side to stake a claim to start in the second leg of the Champions League semi-final with Chelsea.
Benitez's line-up, showing nine changes from the starting XI against Chelsea in the Champions League, had plenty of possession in the early stages and were content to knock the ball around and probe for an opening.
Lucas had the first effort on target from a cross by Andriy Voronin but Blues goalkeeper Maik Taylor was able to save comfortably away to his left as he failed to make full contact.
Forssell showed good skill on the edge of the Liverpool box to manufacture half a chance for himself but his volley flew straight at Jose Reina.
Forssell was looking the most threatening for Blues when the ball was played into his feet and good skills by the Finnish international found Olivier Kapo in space on the left of the Liverpool box.
But the former Juventus player opted to strike the ball first time and his shot flew into the side netting.
Kapo did better when turning past Steve Finnan and getting to the byline but he over-hit his cross with Forssell waiting in the centre.
Then after 34 minutes the home side went ahead through Forssell's ninth goal of the season.
McFadden was the creator with a teasing cross from the right flank which seemed to glance off the head of Martin Skrtel before finding Forssell unmarked at the far post.
He had time to bring the ball down before hammering it past Reina.
Liverpool tried to retaliate and Taylor was called into meaningful action for the first time to turn aside a dipping powerful 25-yard drive from Crouch.
Voronin became the first player to be yellow-carded after 42 minutes for a touch-line challenge on City skipper Liam Ridgewell.
Then home defender David Murphy was booked in first half injury-time for chopping down Pennant but, fortunately for Blues, John Arne Riise was inches too high with his 30 yard free-kick.
Benitez would have wanted a more committed performance from his side and Liverpool had most of the possession in the early stages of the second period.
But after 54 minutes St Andrews erupted after a stunning free-kick from Larsson doubled Birmingham's lead.
McFadden was brought down by Skrtel some 25 yards out and before the free-kick was taken both Riise and Hyypia complained that Jaidi was obstructing Reina.
But the keeper had no chance as Larsson's curling effort beat his dive and hit the top corner of the net.
Ridgewell got up well to meet a corner from Larsson but he directed his header past the post when he should have at least hit the target.
But Liverpool gave themselves a life-line after 62 minutes when Crouch made no mistake with a first time drive from the edge of the box after a mazy run by Pennant had created the chance.
It means City have now gone 17 games since last keeping a clean sheet against Middlesbrough on Boxing Day.
Jaidi had a chance to restore City's two-goal advantage but headed Larsson's free-kick wide from close range before Nafti was booked for bringing down Pennant.
But Liverpool were now in the ascendancy and Voronin and Benayoun both wasted decent opportunities.
The visitors were not to be denied and after 77 minutes Benayoun's deflected header brought them back on level terms.
Lucas sent over a teasing cross which Benayoun was first to react to but his header hit Jaidi and wrong-footed Taylor as it trickled into the corner of the net.
Alex McLeish's side had appeared to be coasting to victory after goals from Mikael Forssell and Sebastian Larsson had put them in total command.
But a lethargic Liverpool suddenly came to life and, after Peter Crouch had reduced the arrears, Benayoun's deflected header rescued a point and dealt a massive blow to the home side.
Blues will be wondering how they surrendered two priceless points after appearing to be cruising to only a second win in the last eight matches.
Larsson and James McFadden were a handful throughout for the Reds and Birmingham were also hard to break down - a sharp contrast to the 5-1 mauling at Aston Villa last weekend.
But a failure to keep clean sheets has been an Achilles heel for City all season and they were forced to defend desperately for the final half hour.
Liverpool's inspiration was former Blues winger Jermaine Pennant and he was one of the few players in Rafael Benitez's 'shadow' side to stake a claim to start in the second leg of the Champions League semi-final with Chelsea.
Benitez's line-up, showing nine changes from the starting XI against Chelsea in the Champions League, had plenty of possession in the early stages and were content to knock the ball around and probe for an opening.
Lucas had the first effort on target from a cross by Andriy Voronin but Blues goalkeeper Maik Taylor was able to save comfortably away to his left as he failed to make full contact.
Forssell showed good skill on the edge of the Liverpool box to manufacture half a chance for himself but his volley flew straight at Jose Reina.
Forssell was looking the most threatening for Blues when the ball was played into his feet and good skills by the Finnish international found Olivier Kapo in space on the left of the Liverpool box.
But the former Juventus player opted to strike the ball first time and his shot flew into the side netting.
Kapo did better when turning past Steve Finnan and getting to the byline but he over-hit his cross with Forssell waiting in the centre.
Then after 34 minutes the home side went ahead through Forssell's ninth goal of the season.
McFadden was the creator with a teasing cross from the right flank which seemed to glance off the head of Martin Skrtel before finding Forssell unmarked at the far post.
He had time to bring the ball down before hammering it past Reina.
Liverpool tried to retaliate and Taylor was called into meaningful action for the first time to turn aside a dipping powerful 25-yard drive from Crouch.
Voronin became the first player to be yellow-carded after 42 minutes for a touch-line challenge on City skipper Liam Ridgewell.
Then home defender David Murphy was booked in first half injury-time for chopping down Pennant but, fortunately for Blues, John Arne Riise was inches too high with his 30 yard free-kick.
Benitez would have wanted a more committed performance from his side and Liverpool had most of the possession in the early stages of the second period.
But after 54 minutes St Andrews erupted after a stunning free-kick from Larsson doubled Birmingham's lead.
McFadden was brought down by Skrtel some 25 yards out and before the free-kick was taken both Riise and Hyypia complained that Jaidi was obstructing Reina.
But the keeper had no chance as Larsson's curling effort beat his dive and hit the top corner of the net.
Ridgewell got up well to meet a corner from Larsson but he directed his header past the post when he should have at least hit the target.
But Liverpool gave themselves a life-line after 62 minutes when Crouch made no mistake with a first time drive from the edge of the box after a mazy run by Pennant had created the chance.
It means City have now gone 17 games since last keeping a clean sheet against Middlesbrough on Boxing Day.
Jaidi had a chance to restore City's two-goal advantage but headed Larsson's free-kick wide from close range before Nafti was booked for bringing down Pennant.
But Liverpool were now in the ascendancy and Voronin and Benayoun both wasted decent opportunities.
The visitors were not to be denied and after 77 minutes Benayoun's deflected header brought them back on level terms.
Lucas sent over a teasing cross which Benayoun was first to react to but his header hit Jaidi and wrong-footed Taylor as it trickled into the corner of the net.