Everton go to United today after having travelled to Russia for a midweek Europa League tie.
"I think to come back from Russia and play on Sunday at 12 o'clock is really difficult, from past experience, so I feel United have got to have a fast start and keep the tempo high to make sure Everton feel the effects of the Europa League game," he said.
"Everton have let in too many goals which is unlike them, and every goal has been an individual error. But it was their best defensive performance at Anfield [last weekend] when they cut out the silly mistakes and became hard to beat.
"As for United, it's been a bit up and down. The biggest problem is the amount of injuries - to have nine or 10 out, particularly in key areas of the pitch, means you're always going to struggle. The time to judge this team is when everybody is fit.
"People are having a go at the defence but there have been no centre-backs fit all season. Soon, Phil Jones, Jonny Evans and Chris Smalling will be back and the manager can start playing his best pairing at centre-back. I'm sure these players will come good. I've got every faith in them. I've coached them, played with and against them, and I know the qualities they have got."
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