Former Manchester United goalkeeper Edwin van der Sar says there is no better manager than Sir Alex Ferguson.
Van der Sar, 41, played at Old Trafford under Ferguson between 2005 and 2011 before retiring from football last summer.
Ferguson, 69, marks 25 years in charge of Manchester United on Sunday.
"Mentality-wise, the way he can make you focus on a game and get you to play until the 92nd minute, there is no-one better," said the Dutchman.
"He is the best thing that could have happened to the club 25 years ago."
Van der Sar has also played under Louis van Gaal at Ajax and Carlo Ancelotti at Juventus - but said it was difficult to compare them because, on the continent, the manager is also a trainer.
He added: "I spoke to Ferguson three days ago to congratulate him on everything. It was a really nice conversation and I said it was amazing for him to spend 25 years at a club of that size.
"Then there is the number of players that have come into the team. He is still so enthusiastic about training and the young players coming through."
Following his retirement last summer, Van der Sar says he is enjoying new experiences and will be taking part in the New York marathon on Sunday for the Laureus Sport For Good Foundation.
But he backed his replacement at Old Trafford, David de Gea, after the Spaniard had an indifferent start to life as United's number one goalkeeper.
"I think he had some difficulties at the beginning but you see he has already overcome them," Van der Sar said.
"He has to focus on the thing that brought him to the club, which is his quality.
"I didn't find it hard to settle at United because there was a great bunch of players, great staff and a good atmosphere at the club. He is younger than me and maybe there is more pressure?"
Despite some defensive wobbles this season and trailing Manchester City by five points at the top of the Premier League, Van der Sar thinks his former team can retain the title, which would be their 20th.
He said: "They are without the players who have retired, but they have some younger players they have brought in and hopefully they can do the job."