Milito says that Mascherano would be wasting his time in the second-rate Europa League.
The striker said that Mascherano would be a key signing for Benitez as he seeks to emulate Jose Mourinho's winning ways.
He told the Daily Star Sunday: "I think it's unrealistic of Liverpool to think they can keep hold of Mascherano when they can't even offer Champions League football and are not challenging Manchester United and Chelsea for the Premier League title. "The boss and Mascherano have a good friendship so there were no other clubs on the cards for him after that, including Barcelona. He has wanted to join for a while but when the boss joined Inter I think that sealed the deal.
"Rafa has already made it clear that he wants another season like Jose had with us last season. Javier is a natural-born winner.
"He'll relish being at a club where he will win top honours."