Ellis Harrison’s first goal for the Blues has given Town a 1-0 lead over Sheffield United at half-time at Portman Road.
Town boss Paul Lambert made three changes to his team with Harrison Andre Dozzell and Gwion Edwards all starting.
Dozzell replaced Flynn Downes, who dropped out of the 18, in midfield with Edwards in for Jack Lankester, who was among the subs, wide on the right.
Harrison, who had made two sub appearances since returning from his ankle injury, was making his first start under Lambert with Jordan Roberts also among the subs.
Sheffield United were unchanged from the team which lost 2-1 at home to West Brom eight days ago with ex-Blues striker David McGoldrick starting and former loanee Richard Stearman on the bench.
Blades skipper Billy Sharp hit the game’s first chance in the second minute, the ex-Doncaster man hitting a shot across Dean Gerken from the right of the box, which the Blues keeper just about bundled wide.
From Oliver Norwood’s resultant corner, the ball fell to John Egan in the box but the central defender’s shot was blocked.
The Blades threatened again in the eighth minute, Jack O’Connell crossing from the left and Sharp beating Gerken to the ball but sending it high and wide.
On 11 McGoldrick tried to trick his way into the area but Matthew Pennington forced the ball out of play off the former Blues striker’s toe.
Sheffield United continued to dominate and put the Blues under significant pressure. On 17 Sharp had the ball in the net from a freekick but having strayed offside.
John Fleck struck a low shot through to Gerken in the 20th minute, then on 24 Harrison managed Town’s first effort on goal, a header from a Spence cross which was straight at Blades keeper Dean Henderson.
But the South Yorkshiremen continued to control the game and in the 27th minute Pennington superbly dived to his left to nod behind a dangerous cross from the right. From Fleck’s corner, Egan nodded over when he will feel he ought to have done better.
On the half hour, Mark Duffy cut the ball back past Blues skipper Luke Chambers from the right to Sharp, who turned the ball over when he probably should have hit the target.
Town attacks were rare - as had been spells of Blues possession - but Edwards almost created an opportunity for Sears on the break on 32 but the Welshman’s cross-field pass was too far in front of the ex-West Ham striker and Henderson claimed.
The Blues had the ball in the net in the 35th minute via a Chambers header from a Jon Nolan corner but referee Andy Woolmer had already blown his whistle, presumably for a push.
Although he may have had a case with that decision, referee Woolmer was increasingly irking the ever-more vociferous Town crowd with a number of highly-contentious freekicks having been awarded to the Blades.
Despite the visitors’ dominance, the Blues took the lead in the 39th minute. The Blades gave the ball away on the Town left - a rare occurrence - and Sears fed Harrison, who hit his first Blues goal over Henderson and into the net with the aid of a deflection.
The Welshman, making his first Town start since mid-September, looked delighted to have broken his Blues duck having signed from Bristol Rovers in the summer.
Trevoh Chalobah was somewhat harshly booked for a foul on Duffy as the half moved into its final five minutes.
Having got their noses in front, the Blues looked a more confident outfit and saw more of the ball in the period’s closing stages.
Just before the whistle, Edwards dallied when he should have played in Harrison ahead of him on the right and lost the ball with the Blues in a promising position.
There was no doubt Town were flattered by the half-time scoreline on the balance of a period largely dominated by the Blades.
However, the visitors were unable to make their dominance count in terms of goals before the Blues took what was at best a half-chance when it came, Harrison appearing to get the benefit of a deflection.
Following the goal, Town got on the ball more in midfield with Dozzell and Nolan increasingly involved and they ended the half on the front foot.
Town: Gerken, Spence, Pennington, Chambers (c), Knudsen, Chalobah, Dozzell, Nolan, Edwards, Sears, Harrison. Subs: Bialkowski, Jackson, Ward, Roberts, Nsiala, Kenlock, Lankester.
Sheffield United: Henderson, Baldock, Stevens, Fleck, O’Connell, Basham, Sharp (c), Egan, Norwood, McGoldrick, Duffy. Subs: Moore, Clarke, Coutts, Stearman, Johnson, Crainie, Washington. Referee: Andy Woolmer (Northamptonshire).