Marseille drew 0-0 with the Red Devils at the Stade Velodrome last month in the first game but Deschamps believes his side can beat United, who are unbeaten at home this season.
“On paper you would expect United to qualify, but we have a little opportunity,” said Deschamps.
“If you look at the match purely from a statistical point of view, United have not been defeated at home for a long time,” Deschamps added.
“They have conceded only one goal in seven Champions League games and are a very strong side, so it is a tough task.
“In addition they are one of four or five teams who have a realistic chance of winning the Champions League.”
