If Crystal Palace scores the first goal, then of course we will see Manchester United have to try hard to damage Palace's defense.
But maybe not, United will do their best and avoid mistakes to avoid conceding an early goal against Crystal Palace. United's defense is stronger at the moment so I don't think they will concede first goal.
Even if they manage to score first, it will not be a big advantage for them, because Manchester United are very good now. Of the main players, only Martial is missing, but he is very often injured, so it is not necessary to consider him the main one. I expect Manchester United to win today, they understand how important it is for them, but I do not rule out that they will want to save their energy for the match with Arsenal, let's see how it turns out for them.