Scholes:
"He was one of the first managers to give young players a real chance.
"And he is trying to do it again now.
"With him the players come first. He never slags anyone off publicly. If he has something to say he does it in the dressing room and it never leaves there.
"He sticks up for us to the hilt. It makes us feel wanted and that's important to us.
Referring to him not showing up for the rsenal match a few years ago: "If you apologise, go and see him and talk to him - there is always room to forgive."
Darren Ferguson:
"I remember him coming into the room and saying he had been offered the job.
"He had been offered jobs before and had turned them down, but he said, ‘I am going to take it, what do you think?' I was gutted because I was in my last year at school, but he was always going to take it. That was always the one that was going to entice him away from Aberdeen.
"I knew the pressure my dad was under was intense, probably from himself as much as anyone else, and I knew how relieved he would be to win the title.
"I knew that if we won the first one we would go on to dominate English football and that is basically what happened."
More:
"It was the best education that a player could get. I only played with Roy Keane a couple of times, I played with Eric Cantona a couple of times, but the thing about them all was that they are all winners and that is something that you have to learn from.
Giggs:
"What Sir Alex has done for me is more than just helping my football career. He has done things for me outside the game.
"When I signed in his office to make it official, he told me ‘You've all the coaches here to help you with football matters. But if you ever need anything outside football, the door's always open'.
"At that time it was tricky for me. My mum and dad were splitting up, so he was someone I could talk to.
"You can't believe someone like that would care so much. One of the things that stood out for me was he knew my mum and dad's names. Little things like that made you want to play for him.
"Everyone sees him as a fierce competitor. Yet, from an early age, I got to see the other side as well.
"He has changed a little bit. I suppose he has mellowed. He doesn't turn on the hairdryer as much but is still as keen and fanatical as ever. You need that to be a winner.
"When I started I saw him in action with the youth team. He'd come to all the youth team and A-team games and if we weren't playing well he'd let us know. You knew you had to apply yourself properly.
"I've fallen out with him so many times. The biggest was when we played at Juventus for the first time and he subbed me at half-time.
"He wasn't happy with the way I was playing. We had an argument, so he brought me off. That was disappointing. But I hadn't performed and he was probably right.
"He doesn't shy away from big decisions and has always done things for the best of Manchester United. If he thinks a player has to leave in order to strengthen the team, that's what will happen.
"When Becks left I was stunned. He was 28 or 29 and we all felt we'd be together until we were 34 or 35. But the relationship those two had by the end, it was probably the best thing for both of them.
"I can't imagine playing for another manager at United. His hunger is still there. He is excited about this current team and really excited about the talent at the club at the moment. I could see him staying for another few years."
Keano:
"For him to keep going is remarkable. He stands out with his will to win, he knows football, he knows his players and he knows his own club inside-out."
Denis Irwin:
"He expected standards to be high and if you didn't reach those standards or you let them slip he would be quick to remind you. He is a fantastic man-manager and great to work under"
Mark Robins:
"He'll be in the job until he stops breathing. I honestly think that he will go on for as long as he can, without a shadow of a doubt.
"He's so passionate and he can't live without football. It's instilled in him and is in his blood.
"I don't think you can ever take that away and the day that happens will be the day he stops breathing.
"To manage United for 20 years is absolutely phenomenal and why should he give it up as long as he is fit and healthy?
"He wants to build another team and that's what he's doing.
"Obviously he's excited about it and it keeps him young. He had all those outstanding players, such as David Beckham, Paul Scholes, Nicky Butt and Gary and Phil Neville, who came through in the early to mid-90s, and now he's trying to build another team.
"The treble team in 1999 was proven but this one is a work in progress.
"That challenge of toppling Chelsea will spur him on and this season they're looking like they're capable of winning the league."
Wenger:
What (Ferguson) has done is a tremendous achievement, unique.
"I have seen half of those years from very close up.
"What his legacy will be, I do not know, but it is a tremendous achievement.
"When you think that the average life of a manager is one year and seven days, and somebody has done 20, it is remarkable consistency.
"It is a remarkable achievement, unique. A unique one in Europe at the top level.
"No-one could say the opposite. It needs tremendous motivation, tremendous stamina, and he has that.
"With the two of us it was more about competitiveness than composure.
"I feel we had some heated times - but time will settle things and there is a respect there now."
David Moyes:
"When I was manager at Preston my mobile phone rang in the team hotel just before we were due to go out and train.
"It was Fergie. He said: ‘Hey you bloody idiot, what you doing?'
"It was about a 14-year-old boy who we had in the Preston Academy and Fergie wanted him. I'd been told about the lad a while back, but he hadn't been mentioned again and Fergie wanted to buy him.
"It made me realise that Fergie was involved in every part of the club. He was trying to sign a lad off me who I hadn't been given information about. That's one thing about Fergie. He's always been really knowledgable about what's going on around him."
Benitez:
"It's amazing to be 20 years at one club — especially when it is a top club.
"What's the secret of his success? He's very clever. I think he's the No 1 manager in England. The Premiership is one of the best leagues in the world so maybe he is No 2 or No 3 in the world.
"He is a nice person. I've travelled with him to some Uefa coaching sessions and he is very good company."
Former Scotland manager Andy Roxburgh:
"I played alongside him Falkirk. He had that mentality to be a winner as a player and nothing has changed.
"From an early age he decided he wanted to learn as much as he could about football and stay in the game as long as possible.
"He had the highest coaching licence in Scotland before he even stopped playing. He had the desire and commitment to be trained and then to continue to educate himself. When he was at the SPL meeting in October he told me how stimulating he had found it and the importance of never wanting to stop learning.
"He has that open-mindedness to constantly develop and change.
"He has continually succeeded in re-inventing himself. The trick is to do it every day - in other words to grow - and he continues to do that."
Mark Hughes:
"I know the pressure he has had to endure over such a long period, so for him to keep driving himself forward and driving his team forward is a fantastic achievement."
Stuart Pearce:
"He is a shining light for any young manager who wants to progress. He is probably second to none for what he has done but you can still see that burning ambition in his eyes."
Steve Coppell:
"For what he knew was going to be a massive occasion, to change a player he had previously shown a massive allegiance to, showed that cold, cutting edge that all top managers need."