Last month, this column looked back on the infamous moment when Roy Keane and Manchester United parted ways following a trophy-laden 12-year association.
His Old Trafford departure in November 2005 meant that Keane, who at the time was recovering from a broken foot sustained in a challenge with Liverpool attacker Luis Garcia, was a free agent.
The availability of a player of such distinction and experience caused a clamour, with the likes of Everton, Bolton Wanderers, Juventus and even Real Madrid thought to be keen on the Irishman's services.
Indeed, Keane's former United teammate - David Beckham - was eager to be reunited with the midfielder at the Bernabeu.
"If we have a chance to sign Roy Keane, then I'd say yes. We've got great leaders here already but I have never played with a better leader," the England skipper told reporters.
"Roy Keane would help in any team. He is an incredible player, this is a great club and everybody would want to come here."
Yet, Keane rejected Madrid's advances, admitting in his recent autobiography The Second Half that he had a "fear of the unknown".
Instead, it was on this day nine years ago that the Cork-born player finalised his next move when he penned an 18-month contract with Scottish outfit Celtic.
"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," said Keane, who had in 1999 said that he would like to end his career at Celtic Park.
"Every boy in Ireland has an interest in Celtic, although my English team at the time was Spurs for some reason. I've been up to Celtic to watch a few games and always enjoyed my time here."
Meanwhile, Bhoys boss Gordon Strachan added: "He has proved over the last 15 years that he is a competitor. You can't get enough competitors in your squad and this was too good a chance to miss."
However, despite the initial optimism, Keane's time at Parkhead would not be overly memorable.
He struggled with a long-standing hip problem and although he collected a Scottish Premier League and Scottish League Cup medal, he made just 13 appearances in all competitions before he decided to call time on his career on medical grounds in the summer of 2006.
