Manchester United legend Sir Bobby Charlton says their success is down to everyone knowing whose boss: Sir Alex Ferguson.
Finding the right man to replace him must give the Glazer family sleepless nights.
But, in a new book '19' chronicling all United's record 19 championship successes, Charlton outlines his belief there is no point worrying because getting an indentikit replacement will be impossible.
"There is no point suggesting anybody else to be manager of Manchester United, there is no one around who can fill his boots," said Charlton.
"He is the epitome of everything that is good about Manchester United and the ethos of this club. He knows the game inside out.
"The reason everybody performs to their best is that he is in control, not just of his staff and the first team, but the whole of the club, and as a result it operates in unison.
"I hope he can carry on for a long time yet.
"The record of 19 league titles goes down purely to Alex Ferguson."
Charlton was one of Ferguson's prime backers at the end of the 1980s, when it appeared increasingly likely his time at Old Trafford would be cut short.
The rationale was simple.
"From the very first game that Alex took over the team, you knew that we had such a talented manager, and it was only a matter of time that he would get it right," he said.
