A day after rivals Manchester City made it 21 wins in a row to open up a 15-point gap at the top, the Red Devils were left frustrated in a goalless draw with the Eagles and have won only one of their last five matches in the division.
Chances were few and far between and Ole Gunnar Solskjaer’s side have now gone 285 minutes without a goal heading into Sunday’s derby at the Etihad.
Former United defender Neville was scathing in his assessment of their performance, telling Sky Sports: “They looked lethargic and well off it, their body language looked really drained.
“I thought they’d cement second place by picking up points at places like Crystal Palace. Now Liverpool and Chelsea will think they are in with a right chance.
“It wasn’t a good night for United. It doesn’t matter who’s in charge, you can’t be boring and that was boring tonight.
“They are sleepwalking in games. They are going to end up in a top-four race if they are not careful.”
Additional reporting by PA.