Almost ten years after they had manufactured their last Glentoran shirt, Italian company Diadora were back on board for the 2005 campaign. The design brief was radical, the shirt was made in a figure hugging style and whilst it looked smart on the players it was unforgiving on most supporters. Taken from the Olimpico range the shirt was plain yet effective with a unique high collar and incorporating a small amount of red and black trim. This jersey would get an early season run out in the European Champions League qualifier at Tolka Park in Dublin (in the second leg of the first preliminary round). Glentoran lost the tie against Shelbourne 2-6 on aggregate. The European exit would be a sign of things to come as the Glens failed to lift a trophy all season. Player's names and squad numbers would reappear on the back of a Glentoran strip for the first time since the side played as the Detroit Cougars in 1967. The organisers of the Setanta Cup (a cross border competition in its second year) made the requirement that participating teams must carry squad names and numbers. Glentoran suffered a number of heavy and humiliating defeats during the season resulting in Roy Coyle standing down as manger in the New Year to be replaced by another former player Paul Millar. The shirt's swansong was in the 2006 Irish Cup final defeat by Linfield.
The early start to the 2005/06 campaign in July required Glentoran to register a home and away shirt for European competition. With the much awaited away shirt still in production Glentoran opted to register this red shirt as the third alternative. Supporters first got a glimpse off the new jersey when it was worn in a pre-season friendly against Total Network Solutions in Wales. This design, although the first production red shirt since the mid-Sixties was easy on the eye and also made a pleasant change as an away kit. It was rounded off with a minimal white and grey trim. Glentoran wore it at the Oval for the home leg of the Champions League, but it was never made available for general release, although it was accessible through the shirt sponsorship scheme. This was to be the first cult classic of the new millennium.