"I thought Sir Alex was going to retire three years ago but then he came here and I saw the twinkle was back in his eye," he told the Daily Mail. "That told me he wanted another European title and if he wins it this time, as I hope he does, he may decide he's had enough.
"When it comes to a new manager, United have the pick of the world but there is always a danger top clubs will come calling for Steve.
"If they decided on him or Mark Hughes you'd have no chance of standing in their way. I wouldn't even contemplate doing so if United came in for Steve. I'd be as delighted for him as I'd be sorry for us.
"I'll tell you the job he's done here. When he joined us in November, I honestly thought we would slide out of the Premier League. I feared the worst, so he's earned his bonus. It was an awesome task but he got the players believing in themselves. That's how we managed to take points off Chelsea, Arsenal and Liverpool for the first time.
"With Paul Jewell, I always felt the size of the challenge at Anfield or Old Trafford got to him a bit and he picked a team to keep the scoreline down.
"He gave them too much respect whereas Steve doesn't have any respect for the big guns. He respects them as clubs but sees them as potential scalps when he faces them. That's why we went to Aston Villa last weekend and won. Brilliant, really.
"Sir Alex is football's great maestro, a complete one-off. He opened our ground a few years ago and we do get on. I don't think anyone is really close to him but what Steve and I both have with him is a relationship of respect.
"We got a nice 'Thank you very much' email from him when we drew at Stamford Bridge and I think that result could have cost Chelsea the title.
"It isn't over yet, though. Talk of us rolling over now we're safe is absolute rubbish. If we can repeat the Villa performance United will have a hell of a fight on their hands."