Town's play-off hopes received a major blow as Millwall left Portman Road with a 1-1 draw. The Blues started very brightly and Owen Garvan celebrated his new contract with a sixth minute goal, but Town allowed the Lions back into the game and on 85 David Livermore headed an equaliser.
Striker Alan Lee returned to the starting line-up after his hamstring problem and, with Jimmy Juan also back after injury, Darren Currie moved from midfield to his role between the Irishman and a midfield four of Juan, Matt Richards, Owen Garvan and Ian Westlake.
Former Blue Andy Marshall was in goal for the Lions, taking his place between the posts at the North Stand end to boos prior to kick-off.
As snow fell, Millwall had the first chance of the game, Paul Robinson heading a freekick to Shane Supple.
But it was Town who would have much the better of the opening exchanges which were almost exclusively played inside the Millwall half of the field. Ian Westlake came close to a goal in the second minute, sliding the ball across the face of Marshall's goal with Lee inches from getting a touch at the far post.
Currie put the ball on to the roof of the net in the fifth minute after seeing a previous effort blocked by Robinson.
A goal took Town only one more minute, Zak Whitbread heading a cross from the left to Owen Garvan 25 yards out, the Irishman, who signed a new contract until 2009 on Friday, taking a touch before lashing a low strike beyond Marshall and into the net for his third goal of the season.
Town continued to have the better of it without creating too many more chances until Juan headed a Currie freekick from the right back into the area to Westlake but the midfielder's mis-hit effort from the edge of the six-yard box was blocked.
Wilnis stopped a Tony Craig shot in the 27th minute after Richard Naylor had failed to get too much distance on a headed clearance. Referee Brian Curson got his book out for the first time on 34 after Alan Dunne had fouled Westlake.
Town were failing to fulfil the promise they had shown in the early stages and Matt Richards's shot from the edge of the box which failed to trouble Marshall was Town's only attempt on goal in the second quarter of the game.
As the break drew close, Marvin Elliott hit a curling effort from 30 yards which screwed wide and into the Greene King Stand.
Town had started the game like a side on a mission to reduce their currently unimpressive goal difference but after Garvan had put them in front had gradually lost their impetus, although the visitors were yet to show any danger in front of goal.
Alan Dunne should have put his side back on terms in the 50th minute after a cross from the left reached him at the far post. However, Scott Barron threw himself in the way of the shot and the ball went behind for a corner.
Town might have increased their lead three minutes later, Alan Lee heading a Currie cross back across the area towards Matt Richards who failed to keep his header down. Lee might have been better off going for goal himself.
On 54 Danny Haynes took over from Matt Richards as the Blues moved to 4-4-2 with Darren Currie dropping back into the midfield. Currie felt he should have had a penalty shortly afterwards as he went to ground after bringing the ball into the area from the right but referee Curson failed to agree.
Just after the hour, Lee headed down a cross from the right to Haynes whose close-range stab goalwards was kept out by Andy Marshall's toe. It was perhaps Marshall's best ever save at Portman Road.
The Blues weren't having all their own way and the visitors were starting to get more and more into the game with Dunne on the right wing proving especially difficult to pin down.
On 66 Town were lucky to escape from a goalmouth scramble with Shane Supple eventually grabbing the ball ahead of substitute Marvin Williams. Two minutes later, Dunne headed Craig's left-wing cross wide.
With 20 minutes remaining, Jim Magilton took over from Lee, the striker having looked a little off his best after a few weeks out of action. Two minutes later Sito replaced Barron who had found Dunne difficult to handle.
Fabian Wilnis picked up a yellow card for a foul on the Millwall left on 84, Jason De Vos heading freekick out for the corner from which the Lions would score.
Town failed to clear Dunne's ball into the box and another scramble developed, De Vos clearing off the line from Marvin Williams but David Livermore eventually heading over the massed ranks of Town defenders and into the net. Although it was the Lions' first shot on target since the opening minute of the game, they had deserved it on their better second half showing.
The Blues seemed to be shaken into consciousness by the goal, the entire team appearing to have become very complacent after going ahead so early. Richard Naylor went up front as Town reverted to a three-man backline.
On 89 Millwall sub Mark Phillips was booked for a foul on Owen Garvan who had been on the end of a number of painful looking tackles.
Town pressed for the winning goal but crosses from Magilton and Currie both flew across the box before Juan headed the ball into the arms of Marshall.
As time ran out, Tony Craig received a second yellow and then a red card for taking too long over a throw-in, prompting virtually the entire Millwall side to surround the referee. Westlake screwed Town's final shot of the game wide soon after. The Blues failed to test Marshall any further despite Shane Supple making his way into the penalty area for a corner.
A poor result from the Blues and a disappointing performance aside from the first 20 minutes. Early on Town looked like they were going to stroll to a comfortable victory against an unimpressive Millwall side. However, as complacent Town seemed to sit back thinking the game was already won, the Lions kept going and pulled themselves into a match which should already have been out of their reach and grabbed a goal which won them a vital point in their relegation battle.
Town's play-off hopes now hang by a thread with victories against Preston and Crystal Palace this week now looking increasingly essential.
Town: Supple, Wilnis, Barron (Sito 72), Naylor, De Vos, Garvan, Juan, Richards (Haynes 54), Westlake, Currie, Lee (Magilton 70). Att: 24,864.