However, since that duo were separated, the battles have become less intense, with even Ferguson and Arsene Wenger able to have a cordial relationship - unthinkable when Arsenal were scrapping with United for the major prizes.
"You have to go back a few years to when it was a bit combustible and Keane and Vieira had that love match in the tunnel," Ferguson said. "It has not been anything like that in the last three years. It has calmed down."
Not that either manager has changed his values, even though Arsenal have not won a trophy since beating United in the 2005 FA Cup final.
"Arsene Wenger has not changed his philosophy. It is his way of doing it and it has paid dividends for Arsenal over a long period," added the United manager. "He has a different type of player now. They are younger but they are still trying to do the same things. They still try to entertain and play the football their way."