Roy Keane joined Celtic on an 18-month deal on this day in 2005.

The vastly-experienced midfielder had unexpectedly left Manchester United by mutual consent a little under a month earlier, with his relations at Old Trafford having come under increasing strain.

As a free agent, the 34-year-old had been linked with several clubs in England and abroad, with David Beckham urging Real Madrid to consider signing the Irishman.

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Keane was greeted by large crowds when his signing was announced (Andrew Milligan/PA)

But instead Keane chose to join the club he had supported as a boy, fulfilling an ambition he had voiced several years earlier to end his career at Celtic Park.

“I gave other clubs a chance and was impressed with them all. But it’s a great move for me. I feel that this is where I belong and I’m here to work hard and win games,” said Keane.

“I’ve been in the Premiership for a long time and feel I have proved myself there and needed a different environment, different teams, different grounds.”

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Keane won a league and cup double with Celtic, scoring one goal (Danny Lawson/PA)

Celtic landed themselves a midfielder who had been part of seven Premiership titles, four FA Cups and of course the Champions League win with Manchester United.

He brought with him a reputation as a fiercely combative enforcer, and his enthusiasm appeared undimmed – something his new team-mates could attest to as he was soon seen criticising what he did not like during matches.

There was plenty to criticise as his debut ended in a shock Scottish Cup defeat to Clyde, but Keane would go on to win the Scottish Premier League and League Cup with Celtic that season.

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Keane won a league and cup double during his time in Scotland (Steve Welsh/PA)

However, they would not see the best of Keane during his time in Glasgow as he suffered with a hip injury.

He was limited to just 13 appearances in all competitions before announcing his retirement in June 2006, a year before his contract had been due to end.