Birmingham fell out of the automatic promotion places after they came from behind to claim a 1-1 draw against Coca-Cola Championship rivals Colchester.
After a dour opening half the Us took the lead when Kemal Izzet tapped home after the influential Jamie Cureton saw his goal-bound chance deflected into his path.
But City, who have not won in the league since Boxing Day, claimed a point when an unmarked Stephen Clemence scored from a Gary McSheffrey corner in the 66th minute.
Blues boss Steve Bruce relegated goalkeeper Maik Taylor to the substitutes' bench in preference of young Irishman Colin Doyle, who made just his second league start for the club, while the Us named an unchanged line-up from the team that defeated Preston 1-0 on their previous outing.
Both sides engaged in a battle for midfield supremacy in the opening exchanges as the Us looked to establish the home form that had seen them record a 13-game unbeaten run at Layer Road - 12 of those ending in victory.
Cureton twice looked to test Doyle early on, first with a 30-yard free-kick and then with a squeezed shot on target but on both occasions the Blues' young shot stopper ably handled the danger.
After a first half devoid of goalmouth action Birmingham almost took the lead on the stroke of half-time when Bruno N'Gotty hit a fierce free-kick that smacked off the crossbar.
After the break Birmingham began in a confident mood with Rowan Vine creating some space before unleashing a well-struck effort which was diverted away from goal by Chris Barker who had anticipated the danger.
Dean Gerken then did well to deny McSheffrey at his near post with a reaction save.
But it was the Us who took the lead in the 55th minute through Izzet.
Chris Iwelumo's smart turn and shot crashed against the post and rebounded to Cureton whose goal-bound effort deflected off a defender and wrong-footed Doyle, leaving Izzet with the simplest of tasks to tuck home the ball.
Bruce responded to the goal by immediately substituting Vine and replacing him with Nicklas Bendtner, who had scored a late winner when the teams met on opening day of the season.
And the visitors were soon on level terms.
Gerken produce a fine reaction save to deny Radhi Jaidi after he planted a headed on target from a free-kick.
From the resulting corner the Blues were level with McSheffrey picking out an unmarked Clemence who guided his header into the net.
The Blues continued to push forward following the goal as the Us' home record looked increasingly under threat.
Cameron Jerome wasted an opportunity in the 77th minute when he screwed his shot wide after getting behind the home defence.
Cureton continued to provide the Us with a creative presence and his one-two with substitute Hogan Ephraim set the striker free on goal only to see his shot across the face of goal expertly saved by Doyle.
And Cureton had another sight of goal five minutes from full-time when he worked himself into the penalty area but thrashed his shot over the crossbar.
But the hosts were happy to take a point from the game and extended their unbeaten streak at home to 14 matches.
Teams:
Colchester Gerken, White, Mills, Brown, Barker, Duguid,Watson, Izzet (Ephraim 78), Jackson, Iwelumo, Cureton.
Subs Not Used: Davison, Guy, Richards, McLeod.
Booked: Mills, Ephraim.
Goals: Izzet 55.
Birmingham Doyle, N'Gotty, Jaidi, Martin Taylor, Sadler,Johnson, Muamba (Larsson 86), Clemence, McSheffrey,Vine (Bendtner 59), Jerome (Campbell 90).
Subs Not Used: Maik Taylor, Danns.
Goals: Clemence 66.
Att: 5,918
Ref: K Woolmer (Northamptonshire).