The Daily Mail says Walsh claimed Ferguson met him in the changing room at the recent Cheltenham Festival and they discussed the current problems at Old Trafford.
The Scot, who retired last summer after 27 trophy-laden years at Old Trafford, said Moyes needs to get rid of a number of under-performing players and replace them with decent signings.
Walsh was talking at an event in County Kildare and said: "I met Alex Ferguson in the changing room on the Friday at Cheltenham before racing and I asked him what was going on and he was telling me about buying this fella and he bought the wrong fella and I said to him that I told you five years ago you had to sell Nani and you wouldn't.
"A lot of the players are the players he inherited from you and he said 'Yeah, a good few of them have to go but it all depends on what shopping he does in the summer.
"To be fair to David Moyes, who wanted the job from Alex Ferguson. You're on a hiding to nothing. How are you going to keep going what Alex Ferguson had, how are you going to make it better? You're not. You're on a one-way ticket before you start."
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