Wayne Rooney has urged Manchester United to resist the temptation to target world superstars such as Cristiano Ronaldo or Gareth Bale because he fears it could prove a huge waste of money.
The Red Devils are in the early stages of a new era under the leadership of manager Ole Gunnar Solskjaer and have been linked with a host of established top-tier players.
And with arch-rivals Liverpool becoming European champions only last week, United are longing to bring back their own glory days and improve substantially on their sixth-place finish in the top flight in 2018-19.
Record scorer Rooney says his old club should be patient, however, and build for long-term success at home and in Europe rather than plot a quick and expensive fix.
Speaking on BBC Five Live's Sportsweek show, Rooney said: "For Ole, the first thing he's got to do is try and build the squad. I don't think bringing one or two players in for over £100million is going to really help with the squad and with the players who are there.
"I think he needs to try and look at maybe five or six players who have got potential to be top players but you're not spending £120-130m on these players.
"I think you're spending £30-40m and then you're trying to improve them, which will also give you longevity out of the players and allow you to build a squad around the five or six new players who come in plus a few of the players who are still there.
"You could bring three players in - you could bring in Ronaldo, Sergio Ramos and [Lionel] Messi, or Gareth Bale for instance - and it's going to cost you £300-350m.
"You'd get maybe two years out of Ronaldo, a couple of years out of Ramos and then you've written that money off.
"The club needs to rebuild with younger players. But obviously they need to be good enough and allow the managers to improve them."
Wales winger Daniel James is set to join from Swansea City after the clubs agreed a deal, with the 21-year-old a player United hope will blossom at Old Trafford.
Disappointing not to come away with the 3 points tonight. Well done to @USeguraCR on his 2 goals and brilliant to see Chris Odoi-Atsem back tonight after his fight against cancer, inspirational— Wayne Rooney (@WayneRooney) May 30, 2019
Always a a pleasure to see my good friend @BSchweinsteiger #DCvCHI #DCU pic.twitter.com/Olv4Liqa04
Rooney, now at DC United, added: "I think the Man United fans will understand they're probably not going to compete for the Premier League next year.
"So, let them have that time, let Ole have that time to build a team for the next two or three years who are going to compete not only at Premier League level but at Champions League level."