'Football will be a lot poorer'

David Gill, Manchester United chief executive, in a statement: "We knew that his retirement would come one day and we both have been planning for it by ensuring the quality of the squad and club structures are in first-class condition. What he has done for this club and for the game in general will never be forgotten. It has been the greatest experience of my working life being alongside Alex and a great honour to be able to call him a friend."

Joel Glazer, Manchester United co-owner, in a statement: "Alex has proven time and time again what a fantastic manager he is but he's also a wonderful person. His determination to succeed and dedication to the club have been truly remarkable. I will always cherish the wonderful memories he has given us, like that magical night in Moscow (2008 Champions League final win)."

Michael Owen, former Manchester United striker, on Twitter: "It's just not sinking in! Manchester United with no Sir Alex just doesn't feel right. What a man and great that it has ended on his terms...his record will surely never be eclipsed. He and the squad had planned to go to Chester Races today. Surely there will be a U-turn? Could be the biggest media circus ever if not!"

Sepp Blatter, FIFA president, on Twitter: "His achievements in the game place him without doubt as one of the greats. Was (an) honour to present Sir Alex with award at 2011 Ballon D'Or. Will his longevity at the top ever be repeated?"

Michel Platini, UEFA president, on uefa.com website: "Sir Alex has made a massive contribution to football, not only in Scotland and in England but across Europe and beyond. His dedication, his attention to detail and his unique eye for talent, as both the manager of Manchester United FC and Aberdeen FC, has brought rich rewards over a 30-year period. His CV is almost unique in a results-based profession that normally focuses on short-term solutions rather than long-term vision.

"He is a true visionary and I hope that, having helped us in the past through various coaching initiatives, he will continue to collaborate with UEFA to share his fantastic knowledge with the next generation of up-and-coming European coaches who all wish to emulate his achievements in the sport."

David Cameron, British Prime Minister, on Twitter: "Sir Alex Ferguson's achievement at #MUFC has been exceptional. Hopefully his retirement will make life a little easier for my team #AVFC (Aston Villa)."

Steve Bruce, Hull City manager and former Manchester United defender, to Sky Sports News: "We're shocked, nobody saw it coming. He's obviously been thinking about it for a long, long time. He will be a big hole to replace. It wouldn't surprise me if it's David (Moyes as next manager) and we wish him well. Whoever takes over...he's going to be some act to follow. It doesn't seem quite right that Fergie won't be in charge any more. I don't think the next manager will do 27 years."