Former Manchester United No2 Steve McClaren doubts their defence is strong enough to win the Champions League.
McClaren believes the loss of Rio Ferdinand to season-ending injury is too big a blow to overcome.
"Manchester United, especially looking at them against Marseille, if they don't have Vidic and Ferdinand back that will hamper their chances of winning the Champions League and winning the Premier League," McClaren told talkSPORT.
"They need them two back or at least one of them. I think [Chris] Smalling can do very well and Jonny Evans is back but a lot depends on their two centre-backs."
