James Meredith's own-goal and Michael Morrison's second-half strike condemned 10-man Millwall to a home defeat in the Sky Bet Championship at The Den on Wednesday night.
The Lions were reduced to 10 men on the half-hour mark after Ryan Leonard picked up a second booking, but Meredith had unfortunately bundled the ball into his own net before that to open the scoring after Che Adams' shot hit the post.
Despite their man deficit, Millwall pressured their opponents in the second-half, but were undone by Morrison's 78th-minute goal.
Neil Harris made two changes from Saturday's 1-1 draw with Bolton Wanderers - one enforced - as Steve Morison returned from injury to replace Tom Elliott, whilst Mahlon Romeo came in for Conor McLaughlin in the right-back slot.
The visitors started the brighter, with Connor Mahoney creating problems down Millwall's left-hand side, but fourtunately, they were to no avail.
With 11 minutes on the clock, Birmingham were in front. Adams turned Shaun Hutchinson and shot - after that hit the post, Jutkiewicz was handily-placed to bundle home, although the last touch may have come off James Meredith.
Jutkiewicz blasted wide just after the midway point of the half, whilst on the half-hour mark, The Lions were reduced to 10 men as Leonard was shown a second yellow card for a challenge on Maikel Kieftenbeld. That meant Harris would bring on Ryan Tunnicliffe in place of Shane Ferguson to bolster the midfield.
Gary Gardner shot over the crossbar 11 minutes before the half-time break, before Jacques Maghoma's trickery allowed him to cross for an unmarked Adams at the back post, but Jake Cooper was there to clear behind. From the resulting corner-kick, Maghoma danced his way through The Lions' defence, but Archer saved.
Adams had Mahoney free on 40 minutes but decided to go for goal amongst a clutch of Millwall defenders, but even with their man disadvantage, The Lions were keeping the ball well and forced a duo of corners just before the break. Determination from Jed Wallace nearly created an opening in the 45th minute, but the cross was cleared.
Two minutes into the second-half Birmingham nearly doubled their lead, but Adams' attempt had the sting taken out of it by Cooper before Archer pushed the ball to safety.
At the other end, outstanding play from Lee Gregory won The Lions a free-kick which was taken by Jed Wallace, but after the winger's kick was parried by Lee Camp, Cooper's follow up nestled straight in the arms of the stopper.
Birmingham were seemingly happy to soak up the pressure from the 10-man Lions and look to hit them on the break - the midway point of the second-half was mainly played in the visitors' half - but Millwall had nothing to show for their endeavour.
Mahoney's last action was to dangerously cross for the awaiting Jutkiewicz on 68 minutes, but Hutchinson bravely headed away from danger. Mahlon Romeo had to deflect an effort from Maghoma behind, before Murray Wallace replaced Hutchinson in the second substitution of the night, with the defender departing courtesy of a nasty cut above his right eye.
With 14 minutes remaining, Birmingham doubled their lead in fortunate circumstances once more, as chaos in the penalty area following a series of deflections allowed the ball to fall at the feet of captain Morrison, who powered home despite the best efforts of Cooper.
Another injury, this time to Gregory, meant Harris had to delve into his substitutes once more, bringing on Aiden O'Brien, but the 10 men battled on - Murray Wallace heading wide on 83 minutes.
Maghoma sliced a shot wide late on in the last action of the game.
Millwall: Archer, Meredith, Hutchinson (M. Wallace 74'), Cooper, Williams, J. Wallace, Gregory (O'Brien 79'), Ferguson (Tunnicliffe 32'), Romeo, Morison, Leonard. Subs not used: Amos, McLaughlin, Karacan, Skalak.
Booking: Leonard, Romeo
Sent Off: Leonard
Birmingham City: Camp, Pedersen, Colin, Kieftenbeld (C. Gardner 78'), Mahoney (Harding 68'), Adams, Jutkiewicz, Dean, Maghoma (Bogle 90+4'), G. Gardner, Morrison. Subs not used: Trueman, Roberts, Dacres-Cogley, Lakin.
Scorer: Meredith og 11', Morrison 76'
Booking: G. Gardner, C. Gardner
Referee: Scott Duncan
Attendance: 11,644 (1,305)