Daryl Murphy's ninth goal of the season sees Town leading Birmingham 1-0 at half-time.
Paul Taylor replaced Stephen Hunt in an otherwise unchanged Town side but with new loan signing Jonny Williams missing from the 18, having picked up a minor knock in training on Friday. The Blues lined-up in a 4-3-3 formation with Taylor up front with Daryl Murphy and Frank Nouble.
Town started brightly, Murphy sending a dangerous ball across the Birmingham box but behind his team-mates, however, the first significant chance fell to the visitors in the third minute. Nikola Zigic’s header found Lee Novak on the left just inside the box but the striker mis-hit his shot well wide.
There was a scare for the Blues in the 11th minute when Tommy Smith was dispossessed by Zigic, who sent Federico Macheda away on goal. Fortunately for Town, Christophe Berra got back to stab the ball away from the on-loan Manchester United frontman.
The visitors went close in the 18th minute when Zigic found Novak on the edge of the area from deep on the right. The ex-Huddersfield man hit a powerful low shot just wide of Dean Gerken’s right post.
Town had most of the ball in a scrappy first half hour but with Birmingham having created the game’s only openings. The Blues’ first opportunity of the afternoon came right on 30 when Berra headed just wide from Aaron Cresswell’s freekick on the left.
On 36 Taylor sent in a dangerous cross from the right which was cleared, then Cresswell played in Nouble on the left of the area but he scraped his shot through to the keeper under pressure.
But a Town goal was only two minutes away. Having been found in space on the right by Taylor, Nouble whipped over a low ball which flashed across the Birmingham six-yard box before reaching Murphy at the far post, where the Irishman tapped home his ninth goal of the season.
Prior to the restart Zigic was shown a yellow card having continued an ongoing dialogue with the official for too long.
Town continued to push for a second in the first half’s remaining minutes, Luke Chambers seeing a cross-shot blocked having left a defender for dead, but were unable to add to their lead.
The Blues had had more of the ball than the visitors during a scruffy half but hadn’t seriously threatened until shortly before the goal, which Birmingham will feel they ought to have defended much better. The Midlanders will also believe they ought to have made more of their earlier opportunities.
Town: Gerken, Chambers (c), Smith, Berra, Cresswell, Skuse, Green, Tabb, Taylor, Murphy, Nouble. Subs: Loach, Anderson, Hunt, Wordsworth, Mings, Richardson, Ebanks-Blake.
Birmingham: Randolph; Spector, Martin, Packwood, Robinson, Caddis, Huws, Lee, Novak, Macheda, Zigic. Subs: Doyle, Burke, Ibe, Howard, Shinnie, Adeyemi, Blackett. Referee: Keith Stroud (Hampshire).