The Spanish side will host the Premier League giants, who have never won the Europa League, on 4 May.
The @EuropaLeague semi-finals lineup is set!
Is the competition @ManUtd's to lose?
— FOX Sports Football (@FOXSportsFC) April 21, 2017
— Manchester United (@ManUtd) April 21, 2017
The first semi-final features AFC Ajax and Olympique Lyonnais.
Both of the second legs will take place on 11 May.
The Europa League Final will be played at the Friends Arena on 24th May in Stockholm, Sweden.