David McGoldrick netted his second goal of the season in first-half injury time to give the Blues a 1-0 lead against Millwall at half-tie at Portman Road.
McGoldrick, Tyrone Mings and Cole Skuse returned to the side with Luke Hyam, Tommy Smith and Kevin Bru all dropping to the bench.
Skipper Luke Chambers moved to centre-half alongside Christophe Berra with home debutant Jonny Parr at right-back and Mings on the left. Dean Gerken continued in goal.
In midfield, another home debutant Teddy Bishop kept his place in the centre of midfield with Skuse returning having been unwell for the game against the Rams. Paul Anderson was on the right and Jay Tabb on the left.
McGoldrick, who missed out at Derby with a dead leg, returned alongside Daryl Murphy up front. There was no place in the 18 for returning midfielder Darren Ambrose, who signed a short-term deal on Thursday.
Former Blues skipper Carlos Edwards started at right-back for Millwall but Lee Martin missed out with a knee ligament injury. Another former Blue Ed Upson and one-time Town loanee Ricardo Fuller were on the bench.
Murphy struck an early shot well wide before a spell of Millwall pressure ended with Jermaine Easter heading over.
The visitors continued to have most of the ball and went within inches of going ahead in the ninth minute.
Scott McDonald played in Scott Malone down the left and the full-back cut across to Martyn Woolford eight yards out, however, Gerken saved his former Bristol City team-mate’s effort with his foot. The loose ball fell to Easter, who slammed a shot on to the bar and high into the air, Gerken subsequently punching before Skuse finally cleared the danger.
Easter hit a shot straight at Gerken on 14, while the Blues presented little further threat aside from a number of low crosses which came to nothing.
Mathias Renegie headed wide in the 23rd minute after the ball had been played back in from the left by Malone, no one having managed to get on the end of an Edwards cross from the right after the former Blues captain had beaten Mings.
As the game moved towards the half-hour mark, Millwall’s Shaun Williams required treatment after a challenge by Mings on halfway, one which angered the visitors’ bench.
Town gradually started to look a bit more dangerous, Anderson flicking a Parr cross into Lions keeper David Forde’s arms, then soon afterwards Berra headed over from a corner.
On 33 Anderson seized on a poor Millwall clearance midway inside the Lions’ half end fed McGoldrick to the right. The striker returned the ball to the midfielder but the ball seemed get caught under his feet as he screwed his shot well wide.
Millwall had another chance to go in front in the 41st minute after Skuse had lost out on halfway, probably having been fouled. Ranegie brought the ball forward and played it wide to Woolford, who shot into the side-netting from a tight angle on the right.
A minute later, the Blues carved out what was their best opportunity up to then. Parr fed Bishop as he broke forward into the area on the right and the midfielder laid the ball wide to Anderson.
The winger crossed to Murphy who didn’t make a clean contact with his header, but Forde was still forced to claw the ball away as it threatened to bounce up into the top corner.
A minute into first half injury time the Blues went in front. McGoldrick did well to get on to Mings’s long clearance before bringing it inside and feeding Bishop, who was tripped as he broke towards the area. The loose ball fell to McGoldrick, who skipped past Alan Dunne and hit a shot across Forde which took a deflection off Mark Beevers, leaving the keeper helpless.
There was no time for the Lions to hit back before half-time and the Blues went in a goal to the good, which flattered them on the balance of the half overall, although they had looked more of a threat towards the break.
Millwall had played the better football for the most part and will rue having failed to take their opportunities, Easter and Woolford both having had chances to put their side ahead earlier in the half.
Town: Gerken, Parr, Mings, Chambers (c), Berra, Skuse, Bishop, Tabb, Anderson, McGoldrick, Murphy. Subs: Bialkowski, Smith, Bajner, Hyam, Bru, Henshall, Sammon.
Millwall: Forde, Edwards, Dunne (c), Beevers, Malone, Powell, Williams, Woolford, McDonald, Easter, Ranegie. Subs: King, Briggs, Webster, Upson, Onyedinma, Gueye, Fuller. Referee: Carl Berry (Surrey).