Town have announced that manager Paul Cook has been relieved of his duties following this afternoon’s 0-0 FA Cup draw with Barrow at Portman Road.
Blues CEO Mark Ashton told the club site: "Firstly, we would like to thank Paul and his team for their efforts in what has been a difficult transition period for everyone.
"I know how much Paul wanted to succeed at this club. However, following discussions with the board, we have decided a change is needed for our long-term interests.
"At this moment, there is no one lined up to replace Paul. There will be an extensive search to find the best replacement for the club. I will communicate more to the media and our supporters on Monday.”
It seems likely that former Colchester manager John McGreal, who joined the Blues as an U23s coach on Thursday, an appointment we understand wasn't made by Cook, will be put in caretaker charge.
Cook, 54, joined the club in March having been appointed by former owner Marcus Evans following Paul Lambert's sacking with the Blues dropping out of the play-off zone during his couple of months in charge.
The summer saw a major overhaul of the playing staff with 19 senior additions coming in along with new backroom staff - first team coach Franny Jeffers, goalkeeper-coach John Keeley and coach Ian Craney joining another first-team coach Gary Roberts - and around 30 players departing.
Despite the Blues having one of the largest budgets in League One, they made a slow start to the season and they have remained inconsistent and currently sit in 11th in the division.
Cook's record in his 44 games with Town reads a disappointing won 13, drawn 17 and lost 14.
The Blues new ownership backed Cook's appointment by Evans but, as reported by TWTD at the time, the man they eyed for the job was Lincoln City boss Michael Appleton, who worked for Ashton and chairman Mike O'Leary at Oxford having previously had links with the pair at West Brom.
Town are likely to look for a head coach rather than an old-style manager and other candidates we understand will come into the reckoning are MK Dons boss Liam Manning - who started his coaching career with the Blues having been an academy player - and Plymouth's Ryan Lowe.