Belgian-born Moussa spent his youth career with Anderlecht, West Ham and Southend United before the midfielder finally broke into the Shrimpers first team in in 2006 as a 16-year-old. He went on to make 90 appearances for Southend before City snapped him up in 2010 on a two-year deal for an undisclosed fee. He scored his first Foxes goal in October of that year in a 3-1 victory over Scunthorpe United but, being deemed surplus to requirements, he joined Doncaster Rovers on loan in February 2011.