Matty Taylor’s goal a minute before the break has given Oxford United a 1-0 half-time lead over the Blues at Portman Road.
Town named an unchanged side with Tomas Holy in goal behind a back three of Luke Woolfenden, skipper Luke Chambers and Josh Earl, while Gwion Edwards and Luke Garbutt were the wing-backs.
In midfield, Flynn Downes was partnered by Jon Nolan with Alan Judge ahead of them behind strike pair Will Keane and Kayden Jackson.
There was one change on the bench with Andre Dozzell taking the place of James Norwood, who underwent a groin operation on Friday.
For Oxford, midfielder Alex Gorrin was back after a ban and replaced Mark Sykes, who dropped to the bench.
Town began the game brightly with Jackson, who was celebrating his 26th birthday, and Edwards both sending in crosses from the right.
The Blues controlled the early stages for the most part although twice Earl, playing without his protective mask for the first time since joining the Blues, gifted the ball to the U’s in his own half before his team-mates helped snuff out the danger.
On nine, Jackson escaped his man and broke away down the right before sending in a low cross which was too far in front of Keane.
Two minutes later, Jackson turned Edwards’s ball to feet into the path of Keane who looked to be in on goal until his first touch took him into the path of an Oxford defender, who cleared the danger.
The Blues continued to have the better of it with Oxford pinned back in their half and as the game reached the 15-minute mark Woolfenden struck a powerful 20-yard strike which was blocked just inside the area.
Town threatened again down the right in the 22nd minute, Jackson cutting a ball back to the edge of the area from where Garbutt smashed a shot over.
Two minutes later, Marcus Browne hit Oxford’s first effort of the game over the bar from a 25-yard freekick.
On the half hour a Judge corner from the left was nodded out to Chambers, whose header was flicked over the bar by a defender.
From the subsequent flag-kick, Nolan eventually stabbed the ball through to Keane in space inside the six-yard box to the left but Oxford keeper Simon Eastwood was able to smother.
Town continued to push for the game’s opening goal and in the 32nd minute Keane crossed low from the right and Downes flicked across the face of goal. Had the midfielder left it Garbutt behind him would have had an easy tap-in.
The Blues kept up the pressure and went close again in the 35th minute, Keane heading wide from a tight angle beyond the far post from Garbutt’s right-sided corner.
Oxford had made little impression from an attacking perspective but in the 36th minute James Henry broke into the area in space from the right but scuffed his shot through to Holy.
Town then attacked down the left, Jackson beating his man then teeing-up Garbutt, whose shot was blocked. Nathan Holland subsequently hit a shot which hit a Blues defender before Garbutt was booked for an attempted foul during Oxford’s previous attack. On 41 Nolan shot wide.
The Blues had dominated the half but a minute before the scheduled end of the half, the visitors took the lead.
A neatly-worked move ended with Cameron Brannagan finding Henry on the right of the area. His low ball across the edge of the six-yard box found Matty Taylor, who beat Holy.
On the balance of play, Town could find themselves very unfortunate to be behind at the break. The Blues had dominated a team who usually control games themselves and had created a number of openings.
However, they had been unable to take them - or force Eastwood into any significant saves - while Oxford’s goal had come via their first passage of passing inside the Blues half.
Town: Holy, Chambers (c), Woolfenden, Earl, Edwards, Nolan, Downes, Garbutt, Judge, Jackson, Keane. Subs: Norris, Bishop, Sears, Skuse, Wilson, Dozzell, Huws.
Oxford: Eastwood, Ruffels, Dickie (c), Moore, Gorrin, Brannagan, Taylor, Forde, Henry, Holland, Browne. Subs: Stevens, Long, Sykes, Mackie. Hanson, Thorne, Agyei. Referee: Scott Oldham (Poulton-le-Fylde).