United beat Astana in their opening game in Group L, before following up with a hard fought draw at AZ Alkmaar in their second outing.
Partizan have also picked up four points from their first two matches and are expected to present United with a stiff test.
United haven’t won away from home in any competition since beating Paris Saint-Germain in the Champions League back in March.
However, they won the Europa League two seasons ago and are unbeaten in their last 13 games in the competition.