Sir Alex Ferguson has criticised Liverpool for rushing the deal that saw Andy Caroll move to Anfield for £35 million.
The Manchester United manager claimed that Kenny Dalglish and the Liverpool board should have done "more homework" before spending a record fee.
The 23-year-old striker is now on loan at West Ham United and Ferguson believes it is up to him to improve himself, though admits that the "big jump" to Liverpool would have been difficult for him.
Ferguson said: "I think it's up to the boy to improve himself. He had only played something like a dozen games for Newcastle and had to deal with a £35 million transfer to a club like Liverpool. I think that was quite a big jump for him.
"I would certainly not be signing a player for that kind of money. We have gambled with young players in the past. Maybe a couple of million.
"But when you get to that level of £35 million, you really need to do more homework and see how he is in the second season for the club he is playing for."
Carroll is in line to face Ferguson's side on Wednesday when they play West Ham.
