Ruben Amorim has insisted the Europa League is 'so much harder' than the Champions League.
United are bidding to win Europe's second rate competition this season, which would see them qualify for the Champions League next season - something they are not going to do via league position.
After making it through the league phase unbeaten, the Red Devils drew 1-1 with Spanish side Real Sociedad on Thursday night in the first leg of their last-16 clash.
They must therefore win the return leg at Old Trafford next week if they are to progress to the quarter-finals, but first have a Premier League match against Arsenal on Sunday to contend with.