Manchester United manager Louis van Gaal says last week's 3-1 win over Club Brugge could not be enough to qualify for the group stage of the Champions League.
The Dutchman has warned his players that they must produce a quality performance at the Jan Breydel Stadium if they are to make it through to the next stage of the competition.
The Red Devils will crash out if they lose by a 2-0 scoreline but will be in a strong position if they score at least one goal away from home.
"We are still not there yet, it's very important," van Gaal is quoted as saying by Sky Sports.
"We have to play the game, at the end you have to have scored more than one goal than the opponent.
"They have beaten Greek opponents 3-0, they are capable of doing that with the support of their fans.
"I don't think my players will take it easy.
"We have had the same preparation and I don't think they shall start differently as last week. Fellaini's goal was very important because now we can start this game with a lot more confidence.
"But as you know maybe we had to finish much earlier also in that game.
"[Fellaini's role this season?] He can play as a no.6 or no.8 but this year he'll be more a no.9 or no.10 as we have players in the other positions."