Roy Keane
celtic by far
No, he left Manchester United in the summer of 2009 to join Manchester City.
Celtic because theyhave a solid team and have a solid line up so it would be celtic
It's your own personal opinion.
2008 ;D
No
Man united signed Wayne Rooney from everyton for 25 million
Manchester Utd. have more combined wins than Celtic do since the first time they played each other , in which Celtic won the first match between the two.
Cristiano Ronaldo left Manchester United FC in 2009 for about 80million pounds to join Spain giants Real Madrid (A world record transfer fee) :)
Manchester United 1 (Rooney 12) Celitc 2 (Brown 24, Samaras 75)
In England
Liam Miller was the last one, a free transfer from Celtic to Man Utd.