David Beckham called Sir Alex Ferguson the "greatest and best manager I ever played under," while Gary Neville called him the "last of a kind," as tributes poured in for Ferguson who announced his retirement as United manager come the end of the season.

Beckham, who has famously enjoyed a tetchy relationship with Ferguson, had no doubts in his mind about the Scot's greatness, while explaining how much Sir Alex had helped him succeed in his early days.

"The Boss wasn't just the greatest and best manager I ever played under, he was also a father figure to me from the moment I arrived at the club at the age of 11 until the day I left," Beckham said on his Facebook page.

"Without him I would never have achieved what I have. After 98 (World Cup) without the manager I would have found it virtually impossible to cope with the attention I was getting on and off the field and for this I will always be grateful to him for his support and protection.

"Thank you Boss and enjoy the rest!"

Neville was among the United greats, along with Beckham, who came from the youth squad in the 1990s and enjoyed so much success on the field. Now a respected pundit in the media, Neville believes there will never be another Ferguson.

"I speak in three different guises," Neville told Sky Sports News. "As a fan I'm sad and gutted for the club because it's a day no Manchester United fan ever wanted to come.

"As a player who played for him I'm grateful and feel privileged to have worked with the greatest manager of all time.

"From our side of things (the media), the game's become a little less interesting because we've lost an incredible character, somebody who always played magnificent football. So it's just a loss all round.

"He made you feel passionate about the football club. He changed the  mentality of every single individual. It's an incredible thing balancing the traditional aspects of life, his upbringing, with being open enough to move forward to be modern and change with the modern game. He's the last of a kind.

"He was very simple in terms of his instruction but you knew full well you were playing at a football club that demanded performance.

"I grew up as a fan in the 70s and 80s when the club were a laughing stock, proclaiming themselves the greatest club in the world but not winning a league championship. Now he's taken them to a point of dominance over 20 years in the right style and bringing through young players.

"There was time to celebrate but pretty quickly he would shift on from victory. That's where the longevity has come from. The job is never complete."

Ronaldo's tribute to Ferguson was short and sweet, saying a thank you on Twitter. "Thanks for everything, Boss," he wrote, while posting a picture of him and Ferguson on the day he signed for United.

Ferguson's man management skills are a stuff of legend, and Paul Ince highlighted just how great the United manager was in getting the best out of his players time and again. "I was one of the fortunate ones who spent six fantastic years at Manchester United," he said. "I remember the day I joined, I failed my medical and I thought my move was going to collapse.

"He treated me like a son and I will never forget that moment. It was great to play under such a man. He was so demanding and his standards were so high.

"Yes, we had our ups and downs but so did most of the players during the 1992/93 season because we were winners, but as far as total respect is concerned, the man was immense and he got the best out of me as a player, that's for sure."