Manchester United boss Erik ten Hag admitted relief after their 2-1 win at Luton.
Rasmus Hojlund struck twice for the visitors, with Carlton Morris bringing the scores level in the first-half.
Ten Hag said: "I think quick up and, as you say, we had good chances with Garnacho and Rashford, it could have been three or four-nil.
"After that we lose some focus and we are not so strict in what we should do and they came more in the game. We dropped too deep and allowed them too many passes.
"We gave some chances away and they got the 2-1. That's no good. But after half-time we picked it up. We had several chances. So many chances one against one. I think it was Garnacho, Rashford again, it was Bruno Fernandes. We had so many chances, it should be 3-1 in these moments.
"Their goal brought the pressure on. They had crosses into the box and shots, but not the chances we had. We had big chances and with our abilities, we should have scored.
"It can always happen, a cross or a corner, you can concede if you don't execute the 3-1.
"We make the progress but also you see we have to stay focused during the whole game. I will not say switch off, but when you do a little bit less, than you get punished.
"We can't afford this. We have to be all-time 100% focused. Do your job together, in and out of possession and then you can control your games. What could have been an easy win was now a difficult win."
