United have suffered their worst start to a Premier League season in 101 years under new manager Erik ten Hag.
With an opening weekend defeat to Brighton swiftly followed by a humbling 4-0 loss away at Brentford on Saturday, United sit bottom of the table.
Meanwhile, Ronaldo’s United future is in serious doubt with the 37-year-old wanting to quit Old Trafford this summer in favour of joining a Champions League club.
Neville, who played with Ronaldo at United, believes the loss of the Portugal forward could damage their chances of a respectable finish this season.
“The problem they have now is if they lose him, there’s nothing left in terms of the goal-scoring part of the pitch.
”I genuinely think if they don’t bring players in or if they bring in poor players in and he leaves, I genuinely think they can finish in the bottom half of the table,” Neville said on Monday Night Football.
“I think that is a bottom-half-of-the-table team. That is a massive statement that may look stupid at the end of the season.
“They are demoralised and shot to pieces, it is really bad in there. They have gone back to default.”