In his 18-year playing career, Keane played for Cobh Ramblers, Nottingham Forest and Manchester United, before ending his career at Celtic. Keane was a dominating box-to-box midfielder, noted for his aggressive and highly competitive style of play, an attitude that helped him excel as captain of Manchester United from 1997 until his departure in 2005. Keane helped United achieve a sustained period of success during his 12 years at the club. He then signed for Celtic, where he won a domestic double before he retired as a player in 2006.