With time running out, Blues finally grabbed an equaliser when James McFadden's cross was headed back across the face of goal for Liam Ridgewell to score from close range.
Ridgewell's goal robbed Spurs of chalking up only their second win at St Andrew's in 24 years.
A brave Blues side refused to concede defeat and they were well their point against a Spurs side which has only lost three of its last 13 games.
Blues, now unbeaten at home in their last eight league matches, do lack goalscoring power. This was always evident and explains why manager Alex McLeish is desperate for a new striker.
There were no early signs of Blues suffering a setback after losing their long unbeaten record at Chelsea in midweek.
Blues were, in fact, the first to threaten danger when Lee Bowyer was set up for a strike but his effort was saved low down by Heurelho Gomes.
With former Blues player Wilson Palacios quickly making an impact in midfield against his old club, Spurs responded with a snap raid which finished with Luka Modric's shot going just wide.
But the best chance fell to Christian Benitez in the 17th minute when the Birmingham striker was put clear by Cameron Jerome. Benitez cleverly left Michael Dawson in his wake but a weak shot was easily saved by Gomes.
It was a golden opportunity that they were to rue but it illustrated Blues' ability to be a serious attacking threat.
Ledley King and Dawson, however, were well in control at this stage as Spurs gave ample proof of their credentials.
Spurs appeared to be applying a wearing down process. Peter Crouch suddenly opened Blues' defence with a subtle pass to David Bentley who saw Joe Hart fingertip his effort away for a corner.
Bentley went close to breaking the stalemate early in the second period, while Crouch stumbled as he shot from eight yards following a pass from the generally quiet Defoe.
The game then became a little untidy with Roger Johnson, Palacios and Bowyer all being booked in a four-minute spell.
Bowyer then made way for recent signing, Michel, to make his first home appearance since his arrival from Sporting Gijon.
But in the 69th minute Spurs finally got on target when Gareth Bale advanced down the left and his low cross was deftly flicked on Crouch to Defoe who hammered a first-time shot past Hart for his 17th goal of the season.
Spurs were seemingly on course for victory but a determined Ridgewell had other ideas as he forced home his 90th-minute face-saver.