United were among the 12 top seeds in the competition and were the very first team selected in Friday lunchtime’s draw in Monaco.
Fenerbahce, Feyenoord and Zorya Luhansk were pitted against them, with all four teams allocated to Group A,
United boss Jose Mourinho has not managed a team in this competition since his Porto side lifted the trophy in 2003.
Southampton, who were among the third seeds, were drawn in Group K alongside Inter Milan, Sparta Prague and Hapoel Be’er Sheva.
The final will be held in Stockholm next May.
Group A: Manchester United, Fenerbahce, Feyenoord, Zorya Luhansk
Group B: Olympiakos Piraeus, Apoel Nicosia, Young Boys, Astana
Group C: Anderlecht, St Etienne, Mainz, Qabala
Group D: Zenit Saint Petersburg, AZ Alkmaar, Maccabi Tel Aviv, Dundalk
Group E: Viktoria Plzen, AS Roma, Austria Vienna, Astra Giurgiu
Group F: Athletic Bilbao, Genk, Rapid Vienna, Sassulo
Group G: Ajax Amsterdam, Standard Liege, Celta Vigo, Panathinaikos
Group H: Shakhtar Donetsk, Braga, Gent, Konyaspor
Group I: Schalke 04, Salzburg, Krasnodar, Nice
Group J: Fiorentina, PAOK Slovan, Liberec, Qarabag
Group K: Inter Milan, Sparta Prague, Southampton, Hapoel Be’er Sheva
Group L: Villarreal, Steaua Bucharest, Zurich, Osmanlispor