Eddie Patterson was sacked as manager of Glentoran following Saturday’s 2-0 win over Carrick Rangers at The Oval.
“I have just been told I been relieved of my duties,” said Patterson, who guided the club to two Irish Cup successes in 2013 and ‘15.
“The board felt it was time for a change because of our position in the league and the types of performances.
“I am disappointed and baffled. I have brought silverware to the club and we are in the League Cup quarter-finals.”
Patterson was appointed Glentoran manager in February 2012.
He said he would take a break from football but wanted to stay in the game.
“We have had so many players out with injuries and I have not been able to pick the same back four for two games this season,” he added.
“We did not play particularly well today, but we plugged away and got the three points.
“But the board has made a decision and I have to adhere to that.
“There is anger there. I believe we have good players at the club but the injury situation has hampered us.”
Two goals in the last 10 minutes gave Glentoran the home win over Carrick.
Skipper Stephen McAlorum slotted home from 12 yards in the 83rd minute and substitute Conor McMenamin made it 2-0 deep into stoppage-time.