Town hit the woodwork twice but their home game with Oxford remains 0-0 at half-time.
Bailey Clements was handed his league debut at left-back - with neither Matt Penney or Hayden Coulson in the squad - with Janoi Donacien on the right and George Edmundson and Toto Nsiala at the centre of the defence. Christian Walton was in goal.
In midfield, skipper Sam Morsy was partnered by Lee Evans with Kyle Edwards on the left and Wes Burns on the right and Bersant Celina behind Macauley Bonne.
Kane Vincent-Young was absent from the bench with manager Paul Cook having said the right-back was touch-and-go for inclusion in the squad at yesterday’s press conference having suffered a shoulder injury on Tuesday.
Following the Last Post ahead of Remembrance Sunday, both teams took a knee - with the usual exception of Nsiala, who raised a fist - to applause from the large Portman Road crowd.
Oxford started the game on the front foot but Town went close to going in front in only the fifth minute when Bonne flicked a header from a Lee Evans corner off the near post.
The game continued in a frenetic manner and a minute later the U’s forced Walton into his first save of the afternoon, the keeper diving away to his left to tip a Mark Sykes shot over the bar.
The visitors continued to see most of the ball and take the game to the Blues and on 14 a Sam Long shot deflected into the arms of Walton.
But five minutes later, the Blues hit the same post for a second time. Clements, showing no sign of nerves on his league debut, brought the ball forward a long way before cutting inside to Celina, who took a touch before hitting a low shot which hit the post, Long clearing the danger.
Town began to see more of the ball and in the 23rd minute Morsy struck a shot from 25 yards which deflected over off a defender. From Evans’s corner on the left, Edmundson nodded wide at the far post.
The Blues were on top - although with passes going astray in the final third all too often - but with Oxford still presenting a threat. On 29 Nathan Holland hit a low cross-shot from the left of the box which Walton snaffled sharply down to his left.
Donacien thwarted Sykes as he tricked his way into the area on 38, then two minutes later Cameron Brannagan was shown the game’s first yellow card for appearing to aim a stamp on Clements having shoved the full-back over as he shielded the ball back to Edmundson. The U’s man could count himself lucky not to be shown a red.
There was a scare for the Blues two minutes later when Holland was found in space running in on goal but Donacien made an excellent if risky challenge to upset the midfielder’s progress, then Nsiala completed the job inside the box.
Oxford manager Karl Robinson evidently felt there had been a foul and took his protests to the fourth official too far and was shown a yellow card.
That was the last action of a well-contested half in which the visitors started the stronger but with the Blues hitting the woodwork twice before the Blues were largely in control from around the midway point.
The Blues had got into good areas down the left but without crosses not finding their man, while too many passes had gone astray in promising positions in the middle of the park.
Perhaps it should be little surprise that the scoreline is 0-0 at the break, three of the last four games between the teams having ended in that result.
Town: Walton, Donacien, Nsiala, Edmundson, Clements, Morsy (c), Evans, Burns, Celina, Edwards, Bonne. Subs: Hladky, Burgess, Harper, Aluko, Chaplin, Fraser, Pigott.
Oxford: Eastwood, Long, Thorniley, Moore (c), Brannagan, Taylor, Sykes, Henry, Kane, Holland, Seddon.Subs: Plumley, Williams, Forde, McNally, McGuane, Agyei, Bodin. Referee: Scott Oldham (Poulton-le-Fylde).