Keane spoke of his delight to return to Forest, 25 years after leaving the club for a successful playing career at Old Trafford.

He told the club’s official website: “I am happy to be back. I am looking forward to it, it’s a big challenge and I’m ready for it.

“Obviously, I had great memories of my career here as a player, the club gave me my chance and I will always remember them for that.

“But it is a different challenge now and I am in a different position coaching the players. I am looking forward to it, a huge challenge ahead and 20 years out of the Premier League.

“It will be tough but I am looking forward to it.”

It was widely expected that Keane would join as assistant to O’Neill, who became the club’s 11th full-time boss since 2011 on January 15, and Forest confirmed his arrival on Monday.

A statement read: “Nottingham Forest are delighted to confirm that former Red Roy Keane has returned to the club as assistant manager.

“Keane, who started his professional football career with the Reds in 1990 and went on to make over 100 appearances in the Garibaldi, joins Martin O’Neill’s backroom staff with immediate effect.”

There had been rumours of Keane returning to management after he and O’Neill left their roles with Ireland in November.

The former Forest midfielder guided Sunderland back to the Premier League during his first season in charge at the Stadium of Light in 2006 before resigning in December 2008 and went on to manage Ipswich from 2009 to 2011.

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