United have so far won both of their matches in the competition and will be the favourites for the game considering Benfica have so far lost both of their games at the hands of Basel and CSKA Moscow respectively.
Mourinho said: "I think the [United] players were convinced in the meeting that we had in the morning, that the results are not the real indicator of the value of a team," he said.
"Benfica have a good team. They will be tricky adversaries for us."
In other news Eric Bailly will miss the game as a result of an injury which he sustained while on international duty with the Ivory Coast national team. Marcus Rojo will also not play but is reportedly nearing a return to action.