Cambridge United lead the Blues 1-0 at half-time, Harvey Knibbs having given the U’s the lead on 24, while Christian Walton saved a penalty from Joe Ironside eight minutes later.
Town named the same team which beat Morecambe 4-0 at Portman Road 11 days ago with Leif Davis and Wes Burns both fit enough to start having returned to training following minor knocks in midweek.
Davis was in his usual role wide on the left with Burns on the right with Harry Clarke, George Edmundson, Richard Keogh at the back and Walton in goal.
Skipper Sam Morsy was alongside Lee Evans in the centre of midfield with Nathan Broadhead and 15-goal top scorer Conor Chaplin behind central striker Freddie Ladapo.
Cambridge made one change from the side which drew 0-0 at Lincoln last week with Knibbs coming into the side for Ben Worman, who dropped to the bench.
Former Blues midfielder Paul Digby skippered, while ex-Town forward Jack Lankester was on the bench alongside one-time Portman Road trialist Shilow Tracey.
Ryan Bennett, released by the Blues' academy at 16, and Suffolk-born Michael Morrison started at the heart of their defence, their first starts for the U’s at the Abbey Stadium since joining - in Morrison’s case rejoining - the club earlier in the month.
Town started brightly and in the third minute Chaplin scuffed a volley from the left of the area after a very long Clarke throw from the right had reached him. Another two minutes later also reached the forward but he was unable to get in a shot.
The game quickly settled into a pattern, Cambridge sitting back in their half of the field as the Blues looked to find a way through them.
On 16, Broadhead, Davis and Chaplin interchanged on the edge of the area on the left as they sought to find space to shoot with the latter eventually hitting an effort which was blocked.
Five minutes later, Evans scuffed a free-kick from 30 yards wide, Clarke having been caught by Digby as he took the ball past the former Town man.
Aside from Walton catching a cross, Cambridge had shown nothing going forward but in the 24th minute they went in front via their first shot of the afternoon.
Edmundson miscontrolled the ball out of play on the Town left and from the throw, Digby played it to Knibbs, who brought it forward down the middle before hitting a powerful shot which beat Walton to his right.
Three minutes after taking the lead, the home side had another opportunity, Knibbs digging out a cross from the left towards Joe Ironside at the far post. Home fans claimed the striker had been fouled by Davis but the linesman’s flag was raised, saving referee Sam Barrott a decision.
But just after the half hour, with Town still to recover from conceding the goal, the U’s were awarded a penalty.
Edmundson clumsily felled Conor McGrandles in the area on the left but play continued and Knibbs found the net. However, referee Barrott had already blown and pointed to spot, much to the home side’s frustration.
Ironside took the kick and hit it low and hard to Walton’s right but the keeper got across to brilliantly tip it round the post. The Blues number one celebrated as he might as his teammates congratulated him.
From the flag-kick, Cambridge claimed another penalty but the ball clearly hit Keogh’s back rather than hand.
On 40, Morsy was booked for bodychecking Knibbs midway inside the Cambridge half with the Blues still huffing and puffing against a determined backline, while the home side were presenting more of a threat on their forays forward.
The half-time whistle was met with cheers and applause by the home fans and by one or two boos from the Town support.
Having started well in control but without being able to create a serious chance, the Blues had allowed Knibbs a free shot at goal at a time when the U's hadn't previously threatened.
The Blues seemed to be rocked by conceding and Cambridge would have doubled their lead had referee Barrott allowed play to continue after Edmundson’s foul rather than immediately pointing to the spot. Fortunately for Town he did and Walton made a very impressive penalty stop.
Town had most of the ball in the Cambridge half in the latter stages of the half but without finding a way through the massed ranks of the Cambridge defence with home keeper Dimitar Mitov still to make a save.
Cambridge: Mitov, Digby (c), Jones, Brophy, Ironside, Smith, R Bennett, Morrison, McGrandles, Knibbs, L Bennett. Subs: Mannion, Williams, Haunstrup, Lankester, Okedina, Tracey, Worman.
Town: Walton, Clarke, Keogh, Edmundson, Burns, Morsy (c), Evans, Davis, Chaplin, Broadhead, Ladapo. Subs: Hladky, Harness, Jackson, Hirst, Edwards, Humphreys, Donacien. Referee: Sam Barrott (West Riding).