United headed out to the Portuguese capital with a virtually fully-fit squad. New club captain Gary Neville, who missed Saturday's win over Portsmouth with a thigh injury, should be fit.
John O'Shea is also expected to recover from a slight hamstring strain.
Benfica have their injury problems ahead of the crunch clash. The Portuguese giants will be without strikers Fabrizio Miccoli and Simao Sabrosa as well as midfielder Giorgios Karagounis, all out injured - and boss Ronald Koeman acknowledges the situation is far from ideal.
MANCHESTER UNITED: Van der Sar, Howard, Neville, Brown, Ferdinand, Silvestre, O'Shea, Bardsley, Richardson, Ronaldo, Giggs, Park, Scholes, Smith, Fletcher, Van Nistelrooy, Rooney, Saha.