Ole Gunnar Solskjaer’s side know they cannot afford any lack of focus against their Danish rivals in just one set, with the winners advancing straight to the semi-finals.
As for the first team news, Diogo Dalot and Victor Lindelof are again in contention for United, but Phil Jones, Axel Tuanzebe and Luke Shaw are absent.
Below, our MEN United editors pick their squads to face Copenhagen.
United have used the Europa League as a platform to rotate their squad throughout the season, but with competition now their only focus, it should be a return of the strongest possible team on Monday night.
Romero gets the nod ahead of De Gea in goal on form as well as his cup role, while Bailly is expected to pair Maguire with Lindelof still not fully in shape from the start.
Fred and McTominay didn’t try their luck against LASK last week, so it should be a return to the proven trio that have been playing so steadily since football restarted two months ago.
Up front there are arguments for Mata and Lingard to feature, but their roles should be off the bench with Greenwood, Rashford and Martial the best attack available.
United’s performance against LASK was not spectacular but they got the job done. More importantly, the game proved Solskjaer what his strongest XI is.
McTominay and Fred didn’t make an impact, which means Matic and Pogba should return. Bruno Fernandes should also be eager to leave after receiving a well-deserved rest.
Lingard behaved admirably and was unhappy to be substituted, but Rashford and Greenwood cannot be overlooked due to their recent form. Martial is also playing at the top of his game and will desperately need more goals.
Romero is the deserving starter and David de Gea’s recall would result in cuts, in that he would suggest he remains No.1 for next season when Dean Henderson owes his shot.
Bar Romero and Brandon Williams are United’s top XI picks. None of the starters against LASK Linz last week did anything to suggest from a distance that they should start tonight and almost any outfield change automatically makes United weaker.
Aaron Wan-Bissaka, Victor Lindelof, Nemanja Matic, Bruno Fernandes, Mason Greenwood and Marcus Rashford have not played for 15 days and this has to be seen as a plus.
Choose your team to take on Copenhagen using the selector above.