Former Manchester United defender Paul McGrath feels they were fortunate to nick a win at Arsenal.
But the Aston Villa legend was impressed by United's young defence.
He told the Daily Mail: "Let's be honest, they got out of jail.
"At times against Arsenal it was like the Keystone Cops - they were hacking it clear when they should have been brave and passed it.
"They were so nervous, but then I thought, 'You're doing the right thing, take no chances'. They sensed Arsenal had missed their opportunity. Young Paddy McNair relaxed and grew into the game and Chris Smalling seemed to relish the responsibility of being the senior defender. In the end, for a young defence, it should have done them a world of good."
