Ralf Rangnick says the Manchester United board must let the next permanent manager rip up the squad in the summer if they want to challenge Manchester City and Liverpool.

United are in the process of interviewing candidates for the job, including Ajax manager Erik ten Hag and Paris Saint-Germain coach Mauricio Pochettino. Rangnick says he has already advised the board that the new man needs significant backing in the transfer market while also recommending the club sign more "physical players."

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"Both teams of Manchester City and Liverpool, those two teams have been built together and recruited over a period of five or six years, all of them under the premises of how do the coaches want to play," said Rangnick. "This is what has to happen. That far, I can go right now. I told the board this is what has to happen.

"Whenever the new head coach is clear, it has to be: 'How does he want to play and what kind of players do we need for that?' Then we come back to DNA, speed, physicality, tempo -- what do we need? This team does not lack technical players; it can do with more physicality."

The 1-1 draw with Leicester City on Saturday has left United seventh in the table and in danger of missing out on a place in the top four. With eight games left this season, they are already more than 20 points behind leaders Manchester City and Liverpool, and Rangnick believes it could take three transfer windows to catch up.

"It takes right decisions and where you want to go to -- what kind of players, what kind of manager -- and then in every transfer window try to get the best possible," added the German interim coach. "This is possible. This is not rocket science. It has to be done, and if that happens, it does not necessarily need three or four years, maybe two or three transfer windows, then the situation could be different."