Carlisle United winger Andy Welsh will be out for approximately six weeks with a torn calf muscle.
Welsh, 27, who was diagnosed with the injury last Friday after a scan, will not train with the squad for the minimum of a week.
Meanwhile the club have also confirmed that midfielder Paul Thirlwell, 32, is set for a scan to assess a calf injury.
Thirlwell was withdrawn from Saturday's 1-1 draw at Walsall with the problem.
United are hopeful that long-term absentees Frank Simek and Paddy Madden can return to training after respective thigh and foot injuries.