One goal is more than enough, as long as you beat the other team and you have a chance to continue to next stage, that's enough. Next opponents will not be so easy, Barcelona, Ajax, and many other great clubs from UCL is coming to Europa next up, and that's going to be very tough, they shouldn't tire themselves out on Europa, they will be very tired when the time comes plus Premier league is still going on and they are winning there, so it will be very important to keep both sides going, and I think FA cup will be very tough too.
~
As I understand it, already at the stage of play-offs for the right to play in the 1/8 finals, maybe we will see epic matches, for example, United - Barcelona, if United cannot take first place in their group. It will be interesting to watch such high-profile pairs, and in less balanced ones, almost all representatives of the Champions League will most likely win, like last year.