United lost the home leg 2-0 and will need to make history to progress.
No club has ever advanced in the knockout phase after losing at home by two or more goals in the first leg.
“Goals always change games. We’ve got to get the first goal and then anything can happen,” Solskjaer said.
“Football is a technical and tactical game but it’s also a mental game. If we get the first one we would start believing more and then they might start doubting themselves.
“It’s never mission impossible. It’s just more difficult.