Paul Scholes has described new Manchester United manager Louis van Gaal as a "mad genius" who will bring the fear factor back to Old Trafford.
The 2012-13 champions finished seventh last year, having sacked David Moyes in April after just 10 months in charge.
"From what I've seen already he looks a bit mad to me. Like a mad genius," the former player told the Independent.
"There's no doubt these players need to perform this year or they won't be there for very long."
Scholes, 39, who briefly joined United's backroom staff after Moyes's sacking, also believes Dutchman Van Gaal requires more new signings if he is to challenge for the Premier League title in his first season.
But Van Gaal has lost the services of experienced centre-backs Rio Ferdinand and Nemanja Vidic, left-back Patrice Evra and veteran midfielder Ryan Giggs - "massive players who have won 30 titles between them," according to Scholes.
"I'm sure he [Van Gaal] would have liked to have signed more players," the ex-England international said. "He's not managed to do that yet. Are the players out there available?
"People still want to play for United. It's huge. You get the chance to win the Premier League, but possibly not this year if they don't make any signings."
Meanwhile, Juan Mata, who signed for United from Chelsea for £37.1m in January 2014, believes the club's main focus should be getting back into Europe.
"We would all love to win the league but the most important goal - what this club needs - is to play in the Champions League again," the Spaniard told the Daily Mail.
"I cannot imagine a Champions League two years in a row without United."
Mata, 26, also looks to have emerged as favoured forward from the "four number 10s" Van Gaal said he had at the club, and is revelling in the role.
"This manager wants passing and movement and triangles. It's how I play my best," the former Valencia player added. "But my mission is to assist and score."