A failure to sign Paul Pogba could lead to an unhappy dressing room at Manchester United, Rio Ferdinand has warned.

Jose Mourinho's side are reportedly willing to pay Juventus €120 million to lure the France international back to Old Trafford, but the Serie A club have dug their heels in over the deal's value.

United were thought to be keen on striking a deal before Sunday's Community Shield against Leicester City, but they are yet to make a breakthrough.

And Ferdinand is concerned that United players who have been expecting to line up alongside Pogba could become disillusioned if the deal is not done.

"As a player in the changing room, you've been thinking for so long: 'He's coming, he's coming'," Ferdinand was quoted as saying by The Independent.

"If he doesn't sign it could have an adverse effect mentally on the players in the changing room. For a short period of time at least.

"It's important they sign him."

Some have suggested United are hugely overpaying for Pogba after seeing him leave on a free just four years ago, but Ferdinand feels the transfer fee will soon be forgotten if the France international leads them to glory.

"Of course it isn't [good business] but, listen, when Chelsea sold [Nemanja] Matic and bought him back for £20m-plus it was the same," Ferdinand added. "It's bigger than that but it's still a loss. That's the way it goes.

"When he comes it's just going to be down to the black and white: Will he perform? Will Manchester United win trophies? That's how you get judged.

"People were saying when I went there that £30m was too much but then we started to win and people now look back and think ‘you know what, it wasn't that expensive’. When you can say you've won six Premier League titles in 12 years, it's okay.

"If he goes there for £100m and in 10 years he wins five titles and earns £100m worth in shirts sales, you'll say 'well done, good business.'"