Rio Ferdinand believes Manchester United will be making a mistake if they fail to sign Jason Sancho this summer, after suggesting they are spurning the chance to sign a player who could become "the best in the world" over the next decade.
Borussia Dortmund announced last month that they will not consider any more offers for Sancho in this transfer window after United failed to meet their deadline to pay their €120m asking price.
Speaking at a BT Sport event at the Olympic Park in London, United legend Ferdinand insisted Sancho was worth the money Dortmund were demanding, as he accepted Dortmund's demands will stretch his former club's finances.
"If you have a chance to sign a player who has all the potential to be the best player in the world for the next ten years and has been the best teenager in the world for the last two years, go and get him," stated Ferdinand.
"We have all seen how good he is now and we can only guess how could he can be at a massive club like United. You are buying him at an age where you can get ten-years service out of him and if he is going to be as good as I think he will be, that has to be a good deal for United.
"You would like to think that a club like United could fund a deal to sign a player of Sancho's quality.
"This is not a normal transfer summer. The window is open and not a lot is happening at most clubs, which says it all about what is happening now
"Clubs are not going to be as frivolous as they were in the past. The situation we have all lived through in the last six months will affect what clubs can spend, but I still feel that one big transfer will lead to a few more around Europe.
"The big clubs with the big revenues can still spend money, but it is the teams below them that will struggle. That gives United, Chelsea and Man City a chance to close the gap on Liverpool if they get their signings right this summer."
United's signing of Bruno Fernandes in last January's transfer window gave Solskjaer's side an injection of invention, with Ferdinand suggesting it highlighted the impact top-class signings can make.
"Fernandes has been a breath of fresh air for the team," he continued.
"Where he has been great is unlocking the imagination of the team. You see Marcus Rashford, Anthony Martial and Mason Greenwood and the minute Fernandes gets the ball, they are off, they know their chance is coming.
"That's what top players do. They change a team and a club with their presence and we have seen that with Fernandes at United."
Chelsea have been among the big spenders in the last month as they have splurged £200m on a glut of new arrivals that included the German duo of Kai Havertz and Timo Werner.
Yet Ferdinand has warned his former England team-mate face inflated levels of expectations as his side prepare for their first Premier League game against Brighton tonight.
"It is doing it the right way. Chelsea have made some signings, but who is to say they will fit in and make a positive difference," he added.
"Frank has had a great first season and I don't think he should be deflated by the last two games. If they had finished fourth and won the FA Cup, that would have been a phenomenal season, but they have still exceeded a lot of expectations given that they had a transfer embargo at the start of the season and lost Eden Hazard.
"Chelsea have been decisive in the transfer market, got two big deals over the line, and more will come. The players they are going for are top class and if they can sign a couple more it has to help them.
"Frank has been a breath of fresh air in the way he has handled himself in the media. He has been open and honest in the way he speaks, but people will try and put more pressure on him next season with these new players arriving."