United reached the Europa League final in typical style, turning a routine assignment into the riddle of the Sphinx before finally scraping home. If they do not play better against Ajax in Stockholm, they could find themselves on the end of a kicking.
It seemed unlikely that Celta could possibly play as badly as they did in last week's first leg, and they did not, starting the game with confidence and conviction. But gradually, United improved, and on 17 minutes increased their aggregate lead, Marouane Fellaini heading home Marcus Rashford's wonderful cross.
For a few minutes United played well enough to suggest that the tie would soon be over, but Celta came again, and created by far the better chances in the second half. In the event, John Guidetti missed them, but then, with four minutes remaining, Facundo Roncaglia headed home Theo Bongonda's cross, and suddenly the game erupted.
Two minutes later, some minor argy-bargy led to the dismissal of Rocaglia and Eric Bailly, and then with ten seconds remaining, Hugo Malo launched the ball downfield, and a flick-on found Clauio Beauvue, who knocked wide for Theo Bongonda. He might have shot, but squared for Guidetti instead, and as time stopped, he contrived to muddle his feet, unable to turn home from close range.
Immediately, the final whistle went, and United were there. Just.