Liam Ridgewell grabbed an injury-time equaliser against Spurs as Birmingham extended their unbeaten home record.
The defender volleyed in from close range in the 91st minute when Cameron Jerome's header across the box caused confusion in the Tottenham defence.
The visitors took the lead in the 69th minute when Jermain Defoe latched on to Gareth Bale's strong left-wing cross to drive a right-foot shot past Joe Hart.
Striker Chucho Benitez spurned two good chances for the hosts in either half.
The point ensures Birmingham maintain their impressive home Premier League record - their last defeat at St Andrews came on 26 September - while Spurs see their advantage in fourth place cut to just one point following Liverpool's victory over Bolton.
The result will frustrate Tottenham boss Harry Redknapp, who has strengthened his defence with the arrival of Younes Kaboul from Portsmouth, while Benitez's wastefulness in front of goal will intensify Birmingham boss Alex McLeish's quest to find a new striker before January's transfer window closes on Tuesday.
Striker Jerome passed a late fitness test, allowing McLeish to name an unchanged starting line-up for the 11th successive match, with new £3m signing Craig Gardner propping up the bench.
Aggression won Birmingham point - McLeish
With on-loan signing Eidur Gudjohnsen given time to settle into his new surroundings following his move from French club Monaco, Redknapp began with the starting XI that beat Fulham in midweek, although striker Roman Pavlyuchenko, the subject of a reported midweek £8m bid by Birmingham, was missing because of injury.
Despite ending their 15-match unbeaten run following their 3-0 defeat by Chelsea on Wednesday, much of Birmingham's excellent mid-season form has come from their obdurate defence.
However, the back four were left exposed when Luka Modric spurned a chance from 10 yards following a mistake from Lee Bowyer on the halfway line in the eighth minute.
With former Blue Wilson Palacios bossing midfield, allowing partner Tom Huddlestone to spread passes across the pitch, Tottenham began to dictate the early tempo.
Despite their clear advantage in possession, the visitors were almost undone by a long ball flicked on by Jerome for Benitez. The Ecuadorian striker turned Michael Dawson before attempting to place his finish past Gomes, but instead he fired meekly straight at the Brazilian.
The half-time interval gave Spurs time to reassess their tactics, with their most promising second-half moves originating on the right flank with the impressive David Bentley, playing in only his fifth Premier League game of the season, causing left-back Ridgewell a plethora of problems.
Horrendous defending cost Spurs - Redknapp
The £15m signing from Blackburn forced Hart into a good save in the 49th minute before Modric bisected Birmingham's two centre-backs with a pinpoint pass into the path of Defoe, but his heavy first touch landed into the path of strike partner Peter Crouch, who struck a poor left-footed shot wide.
But the visitors took the lead in the 69th minute when Bale drove powerfully towards the byeline and his cross was flicked on by a crouching Crouch on the edge of the six-yard box into the path of Defoe, who hammered his finish past the diving right hand of Hart.
Benitez spurned another excellent chance when his shot was blocked by Dawson following a perfectly timed run latching on to substitute Jeff Fahey's pass.
But moments after the fourth official signalled five minutes of injury-time, left-back Ridgewell lashed in Jerome's excellent header from close range.
Birmingham boss Alex McLeish on striker Chucho: "He carved out a great chance in the first half, maybe he should have put his laces through it and it was a powerpuff shot.
"But he's dangerous and if we can get more balls into him in the box, that's when he is really dangerous and comes alive.
"I thought we lacked a wee bit of quality and looked a little one-paced. But it was a marvellous result from a not very good performance from us, our aggression and will to win got us through it."
Tottenham manager Harry Redknapp: "We dominated the game, so I didn't really see the goal coming. It was a poor goal and it was pretty horrendous defending from a team that defended well all day and never were in any danger.
"We were in control of the game, we just had to continue playing the way we were. We had three points in the bag and threw two away.
"But we've only had one defeat in 12 games, so we're not in bad form. I was delighted with he way we played it's not an easy place to come to."
76:55 James McFadden produces a left-footed shot from deep inside the penalty box which goes wide of the left-hand upright.
76:40 Miguel Marcos Madera produces a cross, clearance by Vedran Corluka.
Correction - 75:05 Free kick crossed right-footed by Stephen Carr.
75:05 Stephen Carr delivers the ball from the free kick right-footed from left wing,
75:05 Booking The referee shows Jermain Defoe a yellow card for unsporting behaviour.
Correction - 73:57 James McFadden takes a shot. Liam Ridgewell fouled by Vedran Corluka, the ref awards a free kick. Vedran Corluka gets a block
in. The free kick is delivered right-footed by James McFadden from own half, clearance by Gareth Bale. Jermain Defoe is adjudged
to have handled the ball.
73:57 James McFadden takes a shot. Foul by Vedran Corluka on Liam Ridgewell, free kick awarded. Vedran Corluka gets a block in.
The free kick is delivered right-footed by James McFadden from own half, clearance by Gareth Bale. Jermain Defoe is adjudged
to have handled the ball.
72:46 Christian Benitez takes a shot. Blocked by Michael Dawson. Corner from the right by-line taken by James McFadden, Headed effort
from inside the area by Scott Dann misses to the left of the goal.
71:58 The ball is delivered by Stephen Carr, clearance by Ledley King.
70:43 Barry Ferguson has an effort at goal from outside the area which misses left.
70:15 James McFadden takes a outswinging corner to the near post, clearance by Peter Crouch.
69:24 Effort on goal by Barry Ferguson from just outside the penalty area goes harmlessly over the target.
68:07 Peter Crouch provided the assist for the goal.
68:07 GOAL - Jermain Defoe:Birmingham 0 - 1 Tottenham Jermain Defoe scores a goal from inside the penalty box to the bottom left corner of the goal. Birmingham 0-1 Tottenham.
68:04 Gareth Bale delivers the ball,
66:35 Free kick awarded for a foul by Miguel Marcos Madera on Luka Modric. The free kick is delivered right-footed by Tom Huddlestone
from right channel, Scott Dann manages to make a clearance.
66:06 Free kick awarded for a foul by Cameron Jerome on Gareth Bale. Luka Modric takes the free kick.
65:03 Unfair challenge on Roger Johnson by Peter Crouch results in a free kick. Joe Hart takes the free kick.
63:59 Substitution Miguel Marcos Madera on for Lee Bowyer.
63:59 The ball is crossed by Keith Fahey, Foul by Cameron Jerome on David Bentley, free kick awarded. Heurelho Gomes takes the free
61:55 Booking Caution for Lee Bowyer.
61:46 Lee Bowyer gives away a free kick for an unfair challenge on Wilson Palacios. Free kick taken by Michael Dawson.
61:30 The offside flag is raised against Jermain Defoe. Joe Hart takes the free kick.
60:47 The ball is delivered by David Bentley, clearance made by Scott Dann.
Correction - 59:16 James McFadden fires a strike on goal direct from the free kick.
59:16 James McFadden has an effort direct from the free kick.
59:16 Booking The referee shows Wilson Palacios a yellow card for unsporting behaviour.
Correction - 58:49 Wilson Palacios challenges Lee Bowyer unfairly and gives away a free kick.
58:49 Free kick awarded for an unfair challenge on Lee Bowyer by Wilson Palacios. James McFadden restarts play with the free kick.
57:25 Substitution Sebastian Larsson leaves the field to be replaced by Keith Fahey.
56:37 Booking Roger Johnson shown a yellow card.
55:42 Corner taken by David Bentley,
54:49 Corner taken right-footed by David Bentley, Shot by Tom Huddlestone from 20 yards. Blocked by Scott Dann.
54:42 Centre by David Bentley, clearance made by Roger Johnson.
54:23 The ball is crossed by James McFadden, save made by Heurelho Gomes.
52:39 Peter Crouch has an effort at goal from deep inside the area missing to the left of the target.
48:53 Centre by Gareth Bale, David Bentley takes a shot. Save by Joe Hart.
48:09 David Bentley delivers the ball.
47:41 The ball is crossed by Cameron Jerome, Michael Dawson manages to make a clearance.
46:59 A cross is delivered by Gareth Bale, Lee Bowyer manages to make a clearance.
46:50 David Bentley sends in a cross, clearance by Scott Dann.
46:27 David Bentley delivers the ball.
45:01 The match restarts for the second half.
45:00+1:17 The ref blows to signal half-time.
45:00+0:08 Free kick awarded for a foul by Tom Huddlestone on Stephen Carr. The free kick is delivered left-footed by James McFadden
from right channel, Heurelho Gomes makes a save.
44:08 The referee gives a free kick against Peter Crouch for handball. Joe Hart takes the direct free kick.
42:55 Tom Huddlestone takes a shot. Sebastian Larsson gets a block in.
42:28 Luka Modric crosses the ball, Barry Ferguson manages to make a clearance. David Bentley takes the outswinging corner, Liam
Ridgewell manages to make a clearance.
41:53 Corner taken by David Bentley from the right by-line played to the near post, James McFadden makes a clearance.
40:42 The ball is sent over by David Bentley, clearance made by Roger Johnson. Tom Huddlestone takes a shot. Blocked by Sebastian
39:34 Gareth Bale delivers the ball, clearance made by Scott Dann.
38:26 Jermain Defoe takes a shot. Shot from just outside the box by Luka Modric goes over the bar. Liam Ridgewell gets a block in.
38:00 James McFadden takes a outswinging corner to the near post.
36:58 Short corner worked by James McFadden, clearance by Michael Dawson. Sebastian Larsson takes a inswinging corner to the near
post, clearance made by Peter Crouch.
Correction - 35:51 Jermain Defoe takes a shot. Shot by Luka Modric from outside the box goes over the net. Blocked by Liam Ridgewell.
35:33 Peter Crouch takes a shot. Blocked by Roger Johnson.
35:10 The ball is crossed by Liam Ridgewell, save made by Heurelho Gomes.
34:03 Shot on goal by Wilson Palacios from inside the box goes harmlessly over the target.
32:39 David Bentley takes a shot. Save made by Joe Hart. Outswinging corner taken by David Bentley, Roger Johnson manages to make
31:46 Unfair challenge on Liam Ridgewell by Peter Crouch results in a free kick. Joe Hart restarts play with the free kick.
30:20 Free kick awarded for an unfair challenge on Peter Crouch by Roger Johnson. Gareth Bale takes the free kick.
29:10 Cameron Jerome is flagged offside by the assistant referee. Heurelho Gomes restarts play with the free kick.
27:21 The ball is crossed by David Bentley.
26:13 Centre by Liam Ridgewell, Heurelho Gomes makes a save.
25:28 Effort on goal by Christian Benitez from a long way out goes over the bar.
21:03 Ledley King takes the free kick.
20:12 The ball is sent over by Vedran Corluka, Jermain Defoe produces a header from deep inside the six-yard box that clears the
18:24 Free kick awarded for an unfair challenge on James McFadden by David Bentley. James McFadden restarts play with the free kick.
18:12 The ball is delivered by Gareth Bale.
16:16 David Bentley delivers the ball, Close range headed effort by Ledley King goes wide of the left-hand post. Christian Benitez
takes a shot. Save by Heurelho Gomes.
15:42 Corner taken right-footed by David Bentley.
14:55 A cross is delivered by Gareth Bale, clearance by Liam Ridgewell.
12:07 Unfair challenge on David Bentley by Liam Ridgewell results in a free kick. A cross is delivered by Michael Dawson, Peter
Crouch takes a shot. Scott Dann gets a block in. David Bentley takes a shot. Blocked by Scott Dann. Effort from long range
by Cameron Jerome goes wide right of the target.
10:44 David Bentley sends in a cross, save by Joe Hart.
7:29 Effort from inside the area by Luka Modric misses to the left of the goal.
7:14 David Bentley takes a shot. Blocked by Liam Ridgewell.
5:01 Free kick awarded for an unfair challenge on Lee Bowyer by Wilson Palacios. Barry Ferguson restarts play with the free kick.
3:01 Lee Bowyer takes a shot. Save made by Heurelho Gomes.
1:39 Long distance effort from David Bentley misses to the left of the goal.
0:32 Michael Dawson fouled by Cameron Jerome, the ref awards a free kick. Free kick taken by Michael Dawson.
0:00 The referee gets the game started.
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