After romping home to win the 2012-13 Premier League title, United uncharacteristically finished seventh last season, with manager David Moyes losing his job as a result.
Dutchman Louis van Gaal has since taken charge of first-team affairs but old habits were evident at Old Trafford as United lost their Premier League opener 2-1 to Swansea City.
"I am scared for United. Genuinely scared they could go into the wilderness in the same way Liverpool did in the 1990s," Scholes wrote in his exclusive column for The Independent.
"What do they need? Five players. Five proper players who can hit the ground running and turn round a situation that looks desperate," he continued.
"Let me be clear: I am sick of having to criticise the club which I gave my life to as a footballer. But United need to arrest their decline."
