Latics’ centre-back Dan Burn kept their survival hopes alive by scoring the only goal in the 1-0 victory at St Andrews.
The 6ft 7in defender was in the right place to poke home at close range in the 19th minute and was once again outstanding in Latics defensive rearguard.
Latics created the better chances in the first half and probably should have added to their lead following a series of set pieces.
However, Birmingham made it harder in the second half following the introduction of substitute striker Lukas Jutkiewicz and winger Kerim Frei. But Latics back line defended stubbornly and deserved to pick up the three points.
Latics remain in 23rd place, two points behind 21st place Wolves who have two games in hand. Birmingham remain in 17th place in the Championship table.
Warren Joyce made three changes to the team beaten 1-0 at Blackburn with the suspended Sam Morsy and the injured Shaun MacDonald and Ryan Tunnicliffe being replaced by Max Power, Alex Gilbey and Gabriel Obertan.
The manager once again used Omar Bogle as the lone striker but at least there was some width with Gabriel Obertan and Michael Jacobs in the team.
Craig Gardner had an early shot saved by Matt Gilks, but Latics started brightly and might have gone ahead on 18 minutes when a Michael Jacobs free-kick found Jake Buxton and the defender’s header was goal bound until Che Adams deflected it away.
But from the resulting corner Latics went ahead. Jamie Hanson crossed and Gabriel Obertan headed on before Dan Burn poked the ball past Tomasz Kuszczak at close range.
Latics might have added to their lead when Obertan and Bogle had shots blocked from the edge of the area and Hanson and Jacobs both wasted good free-kick opportunities.
Birmingham rarely threatened, although David Davies did connect with Cheike Keita’s left wing cross on 25 minutes but Gilks saved comfortably.
Birmingham manager Gianfranco Zola cut a frustrated figure and he made two changes at the interval in an attempt to make a breakthrough, with Jutkiewicz and Frei replacing Kieftenbeld and Dacres-Cogley.
Latics were under pressure at the beginning of the half as Zola’s substitutions seemed to be having an impact. The home team were launching long balls to Jutkiewicz who was proving to be a handful but Burn and Jake Buxton managed to contain Birmingham’s top scorer.
Josh Laurent made his Latics debut on 73 minutes replacing Obertan, then James Weir replaced Gilbey on 76 minutes.
Frei fired a free-kick over the crossbar on 79 minutes but Latics were still limiting the home team’s chances.
Birmingham lacked the creativity to breakthrough and the closest they got was when Frei blasted a shot over the crossbar from 20 yards on 89 minutes.
Despite three minutes of added time Latics survived relatively untroubled and they secured an essential victory which keeps them in touch with the teams above them.