Manchester United must bring in fresh faces before sanctioning sales for players including Paul Pogba, former defender Gary Neville has urged.
Pogba, who returned to United from Juventus three years ago, has sparked transfer speculation by saying he feels it is a "good time to have a new challenge somewhere else".
Real Madrid, Barcelona and Juve have all been linked with the France midfielder, with United reportedly rejecting a swap deal involving Neymar proposed by Paris Saint-Germain.
Neville, though, feels Pogba should be allowed to leave if the World Cup winner has decided he wants to move on, but only if replacements are secured first.
"They don't have to keep any player," Neville wrote in a Sky Sports column.
"Manchester United are a better team when Paul Pogba plays but if players don't want to be at the club – that doesn't mean Pogba, he may want to be at the club – you have to get everybody onside and aligned with where you're going.
"Ultimately, that's the first thing Ole [Gunnar Solskjaer] had to do – to work out who was going to be ready for the club moving forward. I'm still unsure on many players.
"I see the speculation... and it looks like it could be moving all the time. You've got to get players in before you let them go because being armed with the money makes you vulnerable.
"For United, it's all about timing and manipulating and manoeuvring to a point where they know they're going to get players in before letting some go. Otherwise they'll become very easy to target in terms of people bumping the money up, which I'm sure they are already."
Daniel James is the only signing made by United since Solskjaer replaced Jose Mourinho, leading to criticism of executive vice-chairman Ed Woodward, who handles transfer business.
United were reportedly keen to bring in the club's first sporting director but, although no appointment has been made, Neville defended the lack of new arrivals at Old Trafford.
"It's difficult to do business, it's not easy," added Neville, who won eight Premier League titles with the Red Devils. "Everyone knows Manchester United want players and price tags will go up. You've got to try and encourage players to come to the club.
"Players don't just jump to sign for any club – they do their homework and get their agents to get to work. They probably have 50 meetings before they sign for a club nowadays. Manchester United will be in the pit with the rest of the sharks looking for the big signings.
"It's difficult for all clubs they all want the same players. They all want Harry Maguire, every single club wants him. Everybody wants Christian Eriksen.
"Players that are being bandied about, there are four or five clubs in for them. They aren't just going to sign for the first club, they'll choose wisely and look at the different aspects.
"Manchester United have got a big job to do in order to get a squad right for a championship challenge. Hopefully that'll start this summer but it's not just bringing players in, it's about getting some out."