Manchester United manager Sir Alex Ferguson's 25-year reign at Old Trafford is unbelievable, according to arch-rival Kenny Dalglish.
Ferguson will mark a quarter of a century in charge of the Red Devils this weekend.
In that time he has won a staggering 37 trophies, including the Champions League twice, the Premier League 12 times as well as five FA Cups and four League Cups.
It has been well documented that the Scot was believed to be close to being sacked - something he disputes - before he had won a thing until Mark Robins scored in an FA Cup third-round tie at Nottingham Forest.
Since then he has gone on to make United the dominant team of the last two decades - a fact which Dalglish said could not be ignored.
"He has been fantastic for Manchester United and I think he has even surpassed the legend that was Sir Matt Busby with the achievements and success he has had," said Ferguson's fellow Glaswegian.
"To be anywhere for 25 years is unbelievable and every success he has had is testament to him and the football club.
"When you remember where the football club was when he came in I think it is a fantastic achievement where he has taken to them now."
Asked whether he thought any manager would remain at one club for 25 years in the current climate Dalglish added: "I don't think you would have seen Fergie lasting 25 years when he came in until Mark Robins scored with a header at Notts Forest.
"But whether anyone does it in future is irrelevant - no-one can take away the achievement he has had."
Chelsea boss Andre Villas-Boas, who is only in his third season of full-time management, admitted he could not see himself staying at one club for so long.
He 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. An opportunity came around and we took it.
"But for any manager, a 25 year spell in one club is fantastic and shows there is tremendous trust in Sir Alex's talent."