The reigning English Premier League champions have been drawn against legendary Dutch side Ajax. The Red Devils have not faced Ajax since a UEFA Cup first-round matchup in 1976-77.
Manchester City was paired with Europa League cup-holders FC Porto. The two sides have never played each other before.
Other interesting ties include Stoke City being paired with Valencia, Lazio squaring off against Atletico Madrid, and AZ Alkmaar facing Anderlecht.
Below is the complete list of matchups in the Round of 32:
Manchester City - FC Porto Manchester United - Ajax Athletic Bilbao - Loko Moscow Metalist Kharkiv - Red Bull Salzburg Valencia - Stoke City Olympiacos - Rubin Anderlecht - AZ Alkmaar Atletico Madrid - Lazio Twente - Steaua Bucharest Schalke - Viktoria Plzen Standard Liege - Wisla Krakow Besiktas - Braga PAOK - Udinese PSV Eindhoven - Trabzonspor Club Brugge - Hannover Sporting Lisbon - Legia Warsaw