Former Manchester United winger Steve Coppell has no doubts Sir Alex Ferguson is the greatest manager in history.

But go back some 20 years and Coppell was querying whether the Scot would last the next 20 months.

"He is the best in business, no question," Coppell told the Sunday Mirror.

"With all the changes there have been in football over the years, all the developments - he has made any transition a seamless one.

"Brilliant management."

However, back in the ­December of 1989, Coppell wondered if he had inflicted severe damage on the future prospects of the manager at the club which he had served with such distinction as an international class winger.

He said: "I was manager at Crystal Palace and we played at Old Trafford. We won 2-1.

"I saw him after the game and he was devastated. He looked white as a sheet.

"He invited me into his ­office afterwards and he was trying to make conversation but his mind was all over the place. I said to my staff that he was on a knife edge.

"He hadn't won anything in three and a half years.

"I then said that what he needed was a cup run of some sort. How that would come back to haunt me!"