Glentoran are looking for a new manager after Alan Kernaghan resigned following Tuesday night's shock defeat to Annagh United.
The Glens crashed out of the League Cup at the second round stage on a 3-2 scoreline.
A statement published on the club's official website read: "Alan Kernaghan tendered his resignation to the chairman and it has been accepted."
Roy Coyle will take temporary charge of the team.
Last month Kernaghan signed former Glasgow Rangers star Nacho Novo - a marquee transfer he hoped would galvanise the Oval outfit.
“This and our other signings demonstrate a clear sign of intent from this club as we seek all work together to re-establish Glentoran at the upper end of the Premiership and compete successfully in the cup ompetitions," Kernaghan said in July.
The East Belfast club's next fixture is on September 10 when they travel to Ards in the Danske Bank Premiership.