United host Barca in the first leg at Old Trafford, before travelling to Camp Nou for the return tie next month.
Solskjaer’s side reached the quarter-finals, after completing a remarkable comeback to dump Paris Saint-Germain out of the competition.
“The tie against United is really difficult.
“They’re a side with a lot history, they’re in good form and it will be an even and open tie.
“We’re not favourites. We have to be careful because they never give up.
“They came back against Paris Saint-Germain. It will be an attractive tie for the public.
“I don’t think the factor of playing home or away is as decisive as it was before.
“In the last eight there are four teams that finished second in their group, so played the second legs in the last round away,” Valverde told Marca.
