Ralf Rangnick says Manchester United will only be able to catch Liverpool and Manchester City if they fix the way they recruit new players.
United head to Anfield on Tuesday 19 points behind their rivals, who remain in the hunt for an unprecedented Quadruple of the Premier League title, Champions League, FA Cup and Carabao Cup.
It is approaching 10 years since United last won the title and they haven't won a trophy of any kind since 2017. Rangnick insists the rebuild under the next permanent manager -- set to be Erik ten Hag -- shouldn't take long, but only if the club has a plan.
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"I don't think a club like Manchester United can afford to take three or four years in order to achieve that [catching Liverpool] -- I don't think that is necessary," Rangnick told a news conference on Monday.
"It will take two or three windows if you know what you are looking for. If you don't know what you are looking for, it is a needle in a haystack.
"If you know what kind of football you want to play and what kind of profiles for each individual position, then it is about finding them and convincing them to come."
Jurgen Klopp took over at Liverpool in October 2015 and finished eighth at the end of his first season. But since then, they have not finished lower than fourth and in 2020 won their first title for 30 years.
"Liverpool finished eighth [2015-16] and the year after they didn't play international football at all, so the full focus in the second season of Jurgen was on the Premier League and the national cup competitions," added Rangnick,
"Then it took two transfer windows. But even in the other transfer windows that came later on there has been a lot of very, very good transfers and signings.
"This is what it is all about. It is not complicated. It is not rocket science. But in order to have the best possible wind, you need to know what your destination haven is. If you don't know that, it is always difficult."
United haven't won at Anfield since January 2016, but are in desperate need of points on Tuesday to keep alive their hopes of finishing in the top four. They are currently in fifth place, three points behind fourth-place Tottenham Hotspur.
The squad travel to Liverpool after a section of supporters sang "you're not fit to wear the shirt" during the 3-2 win over Norwich on Saturday, but Rangnick insists it's unfair to suggest the players are lacking in effort.
"I'm not so sure that this is fair towards the players because I know that they care," said Rangnick. "They suffer after defeats like against Everton and they don't like the feeling to not win games or lose games. But again I can understand the supporters.
"They are frustrated and they had high expectations. They don't understand why things happen. But in the end it's up to the club, the board and the people in charge to analyse that but not now."