The teams are evenly balanced after a 0-0 draw in the first leg of this Champions League last-16 match.

Marseille go into the game on the back of a victory at Rennes, where United manager Sir Alex Ferguson was an interested spectator.

Deschamps said: "If you look at the match purely from a statistical point of view, Manchester United have not been defeated at home for a long time.

"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.

"On paper you would fully expect Manchester United to qualify. But we have a chance, a little opportunity. Football is not about statistics alone."

Marseille lost to Chelsea at Stamford Bridge earlier in the campaign and Deschamps wants an improvement on that performance.

"We made some individual errors, " said the former France midfielder. "What I know is that at the highest level and playing against United they will give us nothing.

"It was a good result for them in the first leg and they are very experienced. Despite our good run in the league this is a very different game for us.

"It is a big step up and we have to come up with the right kind of challenge."

Goalkeeper Steve Mandanda is relishing the task ahead.

He said: "United are a great side but we will be motivated as there is everything to play for.

"When you look at what they have achieved it is inspirational. There is respect for them, not fear. We believe we can achieve a victory."