It was nearly two years ago that Man U captain Roy Keane left the club after a falling out with Sir Alex Ferguson. The details are unknown to this day.
Last summer, Keane took up Sunderland's managerial position. The Black Cats had been on the verge of relegation to League One, but Keane's arrival inspired them to a first-place finish in the Champions League and a promotion to the Premiership.
Manchester United did pick up a win last Sunday—but it was an unconvincing win over a subpar Spurs team. Had it not been for Nani's rocket shot, the outcome might have been even less satisfying.
Against Sunderland, Manchester will try to restore their dominance at home with a readjusted formation, as injuries to Rooney and Saha and Cristiano Ronaldo's suspension have shaken up the roster.
Without those key players, the best United can hope for is another narrow victory.
In a showdown between two managers with such a checkered history, though, the result on the field will be mostly beside the point.