Much praise has been reserved for the youngsters in the United side this season but Sir Alex says that more experienced players will be involved at the Estadio da Luz. His hand will be forced anyway by the loss of Tom Cleverley, who was injured in the first half of Saturday's 5-0 win at Bolton and replaced by Michael Carrick.
"My team in Lisbon might be different on an issue of experience," Sir Alex said. "We've also got Darren Fletcher back fit. He's looking good and did well with Scotland last week. I think we'll need to have more experience in the game.
"The important thing is to qualify. Benfica away from home is the kind of the game you have to respect."