Derry forward Paddy Bradley has been sidelined for the Ulster SFC campaign after suffering a serious knee injury.
The Glenullin clubman sustained a torn cruciate ligament in his right knee in Saturday's game against Bellaghy.
Bradley's absence will be a massive blow to the Oak Leafers, who play Fermanagh in their championship opener.
Enda Muldoon is an injury doubt for the game but Conleth Gilligan will be available for the Fermanagh clash.
Gilligan has received a four-week ban for his sending off in the National League game against Antrim but the suspension will expire before the 22 May clash.