Chelsea boss Andre Villas-Boas has hailed Sir Alex Ferguson's 25 years at Manchester United.
He cannot imagine being at one club as long as Ferguson.
The Chelsea boss, in only his third season as a manager, said: "I thought that I was going to stay at Porto for 15 years but eventually we decided it wasn't going to be like that.
"A chance came around and I took it.
"But for any manager, a 25-year spell at one club is fantastic and shows a tremendous trust in Sir Alex's talent."
Fergie's fellow Scot and Blackburn boss Steve Kean said: "He had massive influence on me. His work ethic I've always admired. You always see him at reserve games."