Fortune joined United as a player in 1999, and went on to make 126 appearances for the Reds over the following seven years, before leaving to join Bolton Wanderers.
The Premier League winner returned to the club in 2012 to start working towards his coaching badges and began his role as assistant coach for United’s Under-23s in July 2019.
Last season was a successful one for the Under-23s, with the side achieving promotion to Premier League 2 Division One. Neil Wood's team were in second spot behind West Ham United when the season was curtailed and subsequently concluded on a points-per-game basis.