Chris Morgan has announced his retirement from the playing side.
The stalwart defender has been forced to admit defeat in his bid to return from a serious knee injury he sustained in October 2010.
The 34-year-old, who made a total of 279 appearances for the Blades, damaged lateral and cruciate ligaments in a Championship encounter against Coventry City.
Many of his games for United were as captain and one of his 15 goals came in the final game of the 2005/06 season when the Blades clinched promotion to the Premiership.
Last season, whilst rehabilitating from the injury, he acted as a coach under Danny Wilson and guided United's Reserves to the Central League Central Division title.
Chris told supporters at the Meet the Coaches evening in Malta "As I tried to step-up my rehabilitation and get as close to match fitness as possible I had to continuously take anti-inflammatory tablets to keep the swelling around my knee down. I think I knew in my heart of hearts that it was time to call it a day.
"Danny and Frank were brilliant with me last season and the decision has been a lot less difficult by knowing I will continue to work in the game in a coaching capacity."