...Arsenal
The 36-year-old takes his side to the Emirates Stadium on Sunday to lock horns for the first time as a manager with Arsene Wenger, the man who for so long provided the biggest challenge to his hopes and dreams at Manchester United.
Keane collected seven Premier League winners' medals during his twelve and a half years at Old Trafford, but was denied three more by the Frenchman and his Gunners side.
Nowhere was the intensity of the battles between the two clubs more concentrated than in Keane's confrontation with Frenchman Patrick Vieira.
The pair enjoyed a simmering rivalry which helped to fuel the passion of their respective sides, and the Irishman admits he loved every minute of it.
He said: "It was brilliant, absolutely brilliant.
"Usually my preparation for a game on a Saturday if we were playing Arsenal would start on the previous Sunday.
"Your body just knew you were going to play Arsenal, just psychologically, your body would get ready for it.
"It was the same for all the players, and I am sure it was the same for the Arsenal players.
"Those games were brilliant, absolutely fantastic, the best. United against Arsenal - if you could go back for one game, then that would be the game.
"They were brilliant, brilliant rivalry, the rivalry between the fans, the players, the managers.
"Both teams were usually fighting it out for the title - it was fantastic. You would give anything to play in one of those games again.
"But stuff like that has gone - those rivalries have gone. They still want to beat each other, but there is not that real intensity that there was then."
