No substitutes at the break made the difference. Surely it was a massive rocket from Carrick. Then we saw a massive change in physicality and effort, which made all the difference.

A goal really, really helped too, of course. For that, United needed a long-awaited slice of luck with the slightly iffy penalty decision for a foul on Matheus Cunha, and a second chance for Bruno Fernandes, who was allowed to retake the penalty after encroachment.

Was that the real turning point in terms of luck for Michael Carrick? Maybe. The long-awaited goal gave the team that much-needed belief, and Bryan Mbeumo was so, so unlucky not to equalise minutes later with a shot that hit both posts and came out.

United were not to be deterred, however, and drove forward as their lives depended on it. It was exactly what a baying Old Trafford wanted to see and the Roma defence began to wilt under the pressure.

Not content with a Champions League point, United surged forward for the winner. And it came courtesy of a resurgent Cunha, who blasted home before jumping shirtless into the crowd. Even a red card for the United hero minutes later did not matter. For once, the force was with United. A two-goal deficit had been stunningly overturned and a thrilling 3-2 win secured.

So where does it go from here? The answer is easy. United just cannot afford to play as badly as they did in that first half again.

They need to start games with the same intensity, passion and power as they displayed in the second half. They really showed they can do it, now they need to show it across a whole 90 minutes.

The real big test now comes against Villa on Sunday. They must power on with the same second-half attitude and register three much-needed league points.

Will they do it? I have absolutely no idea. But for now I really don't care. I am just going to savour a classic United comeback for a few days and then perhaps dream of better times ahead.