Sir Alex Ferguson claims he has "never worked with a better defender than Jaap Stam".
The Manchester United manager makes the statement in an upcoming book entitled 'Gewoon Jaap' (Just Jaap), to be released on Saturday to coincide with the player's testimonial.
In the book, he also admits again that selling the defender was one of the few big errors of his managerial career.
United sold Stam to Lazio in 2001, shortly after Stam made revelations about life in the Old Trafford dressing room in his autobiography 'Head to Head'. It was widely assumed that Stam's book prompted the sale.
However, Ferguson said it was purely a financial decision.
"I sold Jaap to Lazio because of the money that the club could earn," Ferguson said.
"His sudden departure had nothing to do with the publishing of his book. As manager I must look after the club's money. Lazio offered a lot of money and I gave into to that. I regret that.
"It was a huge blunder of mine. I don't make them often. Jaap was extremely popular with the fans. But every manager makes a bad decision at some time."
Ferguson said he remains a huge admirer of the defender, who went on to play for AC Milan and Ajax after his time at Lazio.
"I admired in Jaap's game his speed, his enormous power and he had an exceptional sharp tackle," Ferguson said. "Besides that he also had a great mentality.
"He was always focused and he never slacked, even during training. Others could take an example from that. In one-on-one situations he was the best in the world. I have never worked with a better defender than Jaap Stam."
Stam announced his immediate retirement last October after a 16-year career in which he earned 67 caps for Holland.