Celtic completed the signing of Roy Keane on a free transfer on December 15, 2005.
A month earlier, Keane had unexpectedly left Manchester United by mutual consent after a spell out with injury had coincided with a deterioration in his relationship with manager Sir Alex Ferguson.
Hurt in a challenge from Liverpool’s Luis Garcia in September, Keane’s frustrations at United had grown while on the sidelines.
A further MUTV appearance in early November did even more damage as the United skipper gave a damning assessment of some of his team-mates’ performances in a 4-1 defeat to Middlesbrough.
In 12 full seasons with United, Keane had won seven Premier League titles, four FA Cups and the Champions League, but Ferguson was his usual ruthless self and, as tensions mounted, he cut ties as Keane’s contract was cancelled.
Gordon Strachan’s Celtic pounced as Keane joined the club he had supported as a boy, the midfielder signing an 18-month deal.
He would have to wait until January to make his debut, but it came in a shock 2-1 defeat to First Division Clyde in the Scottish Cup.
After helping Celtic to win both the league and Scottish League Cup titles, Keane retired that summer on medical advice.
The announcement came a month after he had returned to Old Trafford for his United testimonial, a friendly against Celtic in which Keane played 45 minutes for each side.
