Town prevented Championship form side Millwall from recording a club record seventh successive away Football League win as an entertaining end-to-end clash ended 2-2. Jake Cooper gave the visitors the lead in the 27th minute, then after the break the previously goalshy Blues turned things around in two minutes on 52 and 54 via what looked to be a Cooper own goal, although officially credited to Martyn Waghorn, who definitely grabbed the second, but George Saville levelled on the hour and the Lions had a number of chances to win it late on but were thwarted by Bartosz Bialkowski.
Mustapha Carayol, Bersant Celina, Stephen Gleeson and Myles Kenlock returned to the Blues’ starting line-up with Town lining up in a 3-4-3 system.
Jonas Knudsen replaced Cameron Carter-Vickers, who dropped to the bench, in the back three with Adam Webster moving to the right.
Kenlock was the left wing-back with Jordan Spence on the right and Cole Skuse in the centre of midfield with Gleeson. Celina and Carayol were up front with Waghorn.
Millwall, who are unchanged from Friday's 2-0 home victory over Nottingham Forest, included former Blues loanee Ryan Tunnicliffe on the bench.
After a minute’s applause for former coach and manager Bobby Ferguson and ex-player Colin Harper, who both died last week, Town started brightly and felt they should have been awarded a penalty in the third minute when Waghorn was shoved over in the area by Cooper.
It looked far more of a penalty than the one Birmingham were given on Saturday but referee Stephen Martin waved away the protests.
In the 10th minute a cross-field ball from Webster from the right found Waghorn at the far post but Jordan Archer twice saved from close range and the ball cannoned behind off the Town striker.
Millwall threatened for the first time in the 12th minute when Lee Gregory got a loose ball under control in the area and hit a shot which deflected wide off a Town player.
But the Blues had played some good stuff in the early stages, keeping the ball far better than in most recent games, and a minute later Celina fed Skuse on the right of the box. The midfielder cut across but Cooper bundled behind.
Just after the quarter of an hour mark Bialkowski twice found himself in trouble as he looked to kick.
First Chambers over-hit a backpass which the Polish international was able to scamper back and clear. Then, moments later, the Blues keeper dallied on the ball and allowed Steve Morison to dispossess him before grabbing it. The Millwall skipper tried to kick it out of his hands and was penalised by referee Martin.
Carayol came within a couple of inches of a brilliant first home goal for the Blues in the 24th minute, cutting in from the left before smashing a powerful shot just over the bar.
However, it was the visitors who took the lead in the 27th minute. Following a freekick which had been cleared, Ben Marshall crossed from the left and Jake Cooper stepped back off his man to nod a header past Bialkowski.
Two minutes after going behind Waghorn hit a low freekick from the right round the Millwall wall but too far in front of a number of on-rushing Town players and keeper Archer was able to claim.
The Lions should have doubled their lead in the 34th minute when Gregory crossed low from the right to the far post but George Saville was unable to keep the ball down as he slid in.
Millwall had been firmly in control having gone in front and a minute later Gregory crossed from the left and Morison flicked his header across the face and wide. Neither side created another opportunity before referee Martin brought the half to a close.
Town had started well with attacking trio Waghorn, Carayol and Celina presenting a threat. The Blues had looked the more likely scorers until Millwall went in front having looked dangerous from earlier set pieces.
The Lions, looking for a club record seventh successive Football League away win, took charge from there and had chances to extend their lead with the Blues not threatening to get on terms.
Soon-to-be-departing Blues boss Mick McCarthy handed 18-year-old striker Ben Folami his Championship debut at the start of the second half with Kenlock making way. The Australian’s only previous senior match was the Carabao Cup match at Crystal Palace in August.
Spence hit the half’s first shot not too far wide two minutes after the restart, then two minutes later Folami made a strong run forward before feeding Celina on the left but Knudsen’s eventual cross was behind Carayol.
Town had started the second period as strongly as they had begun the first and in the 52nd minute they levelled.
Skuse’s shot was saved by Archer and fell to Folami eight yards out but the sub scuffed his effort. Waghorn slid in as the keeper tried to claim, the ball bouncing up and hitting Cooper’s arm with the luckless defender then appearing to inadvertently divert it over his own line as he fell.
And two minutes later the Blues, who hadn’t scored in their previous four games anywhere and their last five matches at home - a total of 525 minutes without a home goal - netted again.
Waghorn read a poor backpass from Cooper - who had been involved in all three goals and the early penalty incident - and took it wide of the advancing Archer before slipping his 14th goal of the season - or 13th if he isn't awarded the earlier goal - into the net.
But Town’s lead lasted only six minutes. Bialkowski palmed a Jed Wallace cross from the right away from Gregory but it landed at Saville’s feet and the Northern Ireland international smashed a low shot past the Blues keeper and into the corner of the net.
Carayol was booked for a foul on 61 and was then replaced by Grant Ward three minutes later.
What had developed into an exciting game was held up just before the 70th minute as Skuse’s head was bandaged. The midfielder made way for Luke Hyam on 76.
Two minutes later Gregory blazed well wide when he should have scored after exchanging passes with Mahlon Romeo on the right and breaking into the box in the clear. On 79 the Lions made a double change, Morison and Marshall making way for Tom Ellliott and Aiden O’Brien.
A minute later Spence was yellow-carded for a foul, then Gleeson joined him in the book, also for a foul, on 82.
Two minutes later Chambers volleyed Hyam’s cross from the right wide, then on 86 Millwall almost won it.
Bialkowski did superbly to block from Gregory when through. The loose ball fell to O’Brien, who struck a powerful low shot which struck the post. Millwall quickly regained the ball and Elliott headed Romeo’s cross over.
The game was an open end-to-end free-for-all in the final minutes with Knudsen crossing behind a number of Town players in one box before Chambers intercepted a Millwall attack at the other before taking the ball forward and, after it was returned to him, sending in a cross which Archer claimed.
Another brilliant Bialkowski save stopped Millwall from winning it in the final scheduled minute, the Pole getting down sharply to his left to stop from Romeo, then soon after the board had indicated five minutes O’Brien scraped a poor effort wide when in acres of space on the left of the Town box.
Millwall, who had had a day’s longer rest following the previous fixtures, continued to look the more likely winners in added-on time, during which Waghorn was booked for a foul, Bialkowski saving from Jed Wallace. Knudsen blocked Elliott’s subsequent shot and from the resultant corner Saville headed wide.
In the final moments Wallace smashed a shot over before referee Martin brought to a close one of this season’s most entertaining afternoons at Portman Road.
Town, who were warmly applauded off by their fans at the end, started the second half very positively and deserved to go in front.
However, Millwall showed good spirit to get back on terms and in the end looked the more likely winners and will feel they had enough chances to have claimed all three points.
But that would have been harsh on the Blues who were worthy of taking something from the match for the way they came back after the break.
In some ways it was a taste of what might have been. Had Town put in more similarly entertaining performances this season manager McCarthy might not have become public enemy number one and on his way out of the club in the summer. Equally, however, the Blues' more open approach might well have led to an eighth home league defeat of the campaign.
Second-half debutant Folami will be pleased with his debut and did more than enough to be given more time for the first team in the season's remaining weeks.
The result sees the Blues stay 13th - now a point and a place ahead of Norwich who lost 4-1 at QPR - with six games remaining, while Millwall stay eighth a point off the top six.
Town: Bialkowski, Webster, Chambers (c), Knudsen, Spence, Skuse (Hyam 76), Gleeson, Kenlock (Folami 46), Celina, Carayol (Ward 64), Waghorn. Unused: M Crowe, Connolly, Sears, Carter-Vickers.
Millwall: Archer, Meredith, Hutchinson, Williams, Gregory (Onyedinma 90), Romeo, Wallace, Morison (c) (Elliott 79), Saville, Cooper, Marshall (O’Brien 79). Unused: Martin, Tunnicliffe, Cahill, Shackell. Referee: Stephen Martin (Staffordshire). Att: 16,010 (Millwall 1,982).