Van Persie has only just returned to training having been sidelined since February with an ankle injury.
Van Gaal revealed that Luke Shaw is available to play in the match but refused to say if van Persie will make it.
When asked about the fitness of Shaw and Van Persie, van Gaal said: “Shaw I think is training for a lot of weeks already so he can play. Van Persie is another story – this is the first week he has trained with us, with the first team, but maybe we have to think about him.”
Van Persie would be the obvious choice to replace Rooney in any other situation but United cannot afford to play an unfit striker in such a big game.
Van Gaal will also be considering Radamel Falcao for the role having left him on the substitute’s bench for a number of weeks. The Colombian’s loan spell at United has to go down as a resounding failure but he is fit and ready to go should he be called upon. Whatever the decision, the balance of the team is likely to be negatively affected.