Defender recovered from a hamstring injury in time to play a part during the 5-0 demolition of Bolton, but has not been included – along with Nemanja Vidic – for European trip
The centre-half had picked up a hamstring injury during the victory over West Bromwich Albion and went on to miss the clashes against Tottenham Hotspur and Arsenal.
But despite returning for the recent 5-0 win over Bolton Wanderers, the defender has been left out of the squad for the clash in Portugal, with Sir Alex Ferguson possibly having one eye on the match against Chelsea.
Nemanja Vidic, Tom Cleverley, Rafael da Silva and Danny Welbeck all miss the encounter due to injuries, but Jonny Evans and Patrice Evra will make the trip despite having sustained knocks during the win at Bolton.
Manchester United squad: De Gea, Lindegaard; Evans, Evra, Fabio, Jones, Smalling; Anderson, Carrick, Fletcher, Giggs, Nani, Park, Valencia, Young; Berbatov, Hernandez, Owen, Rooney.
United lock horns with Benfica in their Group C opener in Lisbon on Wednesday, with the blockbuster tie against Chelsea to take place on Sunday.