United boss Mourinho is wary of the threat Sevilla pose, however, having witnessed the Spaniards - fifth in La Liga - hold Liverpool to 2-2 and 3-3 draws in the group stage of this season's competition.
"It will be a very difficult match. We are playing against a team that didn't lose against Liverpool home and away," he told reporters at his pre-match press conference.
"They scored goals in Liverpool, drew the match in Liverpool. I say Liverpool because they are an example of a very good team, a good example of an important stadium with a big tradition. Sevilla is a really good team and the result of the first leg is a result that leaves everything open.
"We are not one of the best teams in the competition but when a team arrives in the last eight, anything can happen. When you are in the last 16 it looks really, really far but when you are in the last eight you start smelling semi-finals, the feeling is that you are amongst the best."
Man United are looking to join Liverpool, Juventus, Manchester City and Real Madrid in the hat for the last eight.