Ronny Deila, who will take up his duties at Parkhead this week, was making a reference to the colours of Stromsgodset that would be forever in his heart after nine successful years at the club.
He spoke at half-time during the side's 2-1 victory over Haugesund, thanking fans for the support that allowed him "to grow as a person and a coach". Last season, Deila took the club to its first title in 43 years.
"I am an emotional person so it was difficult to hold back the tears," he said later of his appearance on the pitch.
But he added: "It's a happy day too, not just about sadness. It is beneficial to both parties now but Stromsgodset is in my heart forever. I will always be blue."
Deila will report for duty this week to be united with his assistant, with sources at Celtic insisting an appointment was imminent. The favourite for the post remains John Collins, the former Celtic player and Hibernian manager.
Peter Houston, the former Dundee United manager who is now a scout at Celtic, and John Kennedy, the former player who is a coach at the club, have both been mentioned as possible candidates and may feature in a shake-up behind the scenes.
However, Collins, who has been coaching with the Scottish Football Association, is believed to be the preferred candidate for the No.2 post with preliminary talks having taken place already. Celtic are keen to have someone in place this week with the Champions League qualifiers approaching in mid-July.
The former Scotland midfielder has spoken previously about his desire to be involved at a club after he left Livingston. But he has always insisted that it had to be a long-term project with a strategy of developing players.
Peter Lawwell, Celtic's chief executive, praised Deila's strength in this department when the 38-year-old was officially appointed on Friday.
Deila, too, may have an immediate decision to make on Craig Gordon, the former Scotland international goalkeeper, who has not played since April 2012 but who has undergone a medical at Celtic.
Meanwhile, Celtic will host a charity match between teams featuring former Celtic captain Paul McStay and former Manchester United captain Rio Ferdinand on Sunday, September 7.
"Although I'm now based in Australia, my heart will always belong in the East End of Glasgow," said McStay, who spent his career with Celtic before retiring in 1997. "I can't wait to share another very special day with them."
Ferdinand said: "This game presents a fantastic opportunity to raise awareness and funds to support the underprivileged communities of Glasgow and London."
The proceeds of the game will be split equally between Celtic FC Foundation and the Rio Ferdinand Foundation.