Lindelof joined United early in the summer from Benfica after being heavily linked with a move to Old Trafford in January.

United struggled to maintain a centre-back pairing last season with both Chris Smalling and Phil Jones spending long periods on the injury table.

But Lindelof has struggled to make an impact in pre-season for United this season and has drawn criticism for his performances so far.

And Pardew believes the 23-year-old is finding it difficult playing at a much higher level than he was used to at Benfica.

"They've had injuries in that area," Pardew told Sky Sports. "Smalling never seems to play a full season.

"Jones is always injured so there is going to be huge pressure on Lindelof.

"At the moment I think he's finding it a struggle.

"Benfica in the Portuguese league is not the same level as the Premier League week in week out and the intensity put on centre-backs is very difficult.

"I remember Sir Alex Ferguson saying to me at United because you're Man United your two centre-backs have to deal two-on-two and one-on-one because you're going to commit all your players forward to try and win the game.

"His one-on-one play worries me for Man United because I fancy if my man was fit [pointing at Ian Wright] he would have a good chance."