Neville insists they still need a right back and another midfielder before they can claim to be legitimate challengers.
"Unless two or three players come in I don't think it's realistic that he [Van Gaal] can win the league this year," he told Sky Sports.
"Although there is a potential with what Liverpool did in the fact they had free weeks of Saturday to Saturday, continual perfect preparation. That's a big advantage for United if they get onto some momentum.
"In Chicharito, [Wayne] Rooney, [Robin] Van Persie and [Danny] Welbeck, they have still got, I think, probably the best strikers in the league as a pool.
"If they can get the back right and find a solution in midfield - [Michael] Carrick's out for two or three months so they need to sign another top midfield player - and stay injury-free then they do have a chance."
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