Manchester United only need a couple of good transfer windows to get them playing to a similar standard as Liverpool, interim manager Ralf Rangnick said on Monday.
Liverpool have won the Premier League, Champions League, League Cup, Super Cup and Club World Cup over the last four seasons, a period during which United have failed to claim a single trophy.
Rangnick told reporters ahead of their game against Liverpool at Anfield later on Tuesday that the success of United's rebuild would depend on deciding on a style of play and bringing in the players who can make it work.
"I don't think that a club like Manchester United can afford to take three or four years in order to achieve that, and I don't think it is necessary," he said.
"If you know what you are looking for it will take two or three transfer windows. If you don't know what you're looking for you'll always be looking for the needle in the haystack.
"If you know what kind of football you want to play and what kind of profiles you want for each individual position, then it is about finding the players and convincing them to come. It's not that complicated, it's not rocket science."
Liverpool claimed their first top flight league title for 30 years in 2020 but Rangnick said it was unlikely United would be forced to wait a similar period.
"I suppose that will not happen because it is pretty obvious what needs to change and there needs to be a rebuild for the future," Rangnick said. "I don't think that this will happen."
United are fifth in the league, three points behind Tottenham Hotspur, who are in the last Champions League spot.