Sunderland boss Roy Keane admits he could've joined Sam Allardyce's Bolton Wanderers when he left Manchester United.

Keane said: "I wouldn't say I know Sam well, but I spoke to him when I left United because he was interested in taking me to Bolton.

"I gave other clubs a chance and was impressed with them all - but Celtic was a great move for me.

"I'd been in the Premiership for a long time and felt I had proved myself there and needed a different environment, different teams, different grounds."