Schweinsteiger has not played for Man United since January having suffered a knee complaint, while Valencia underwent surgery last year on a foot injury.
Van Gaal confirmed that Valencia has trained for a week and could make the bench against Liverpool on Thursday, while Schweinsteiger has one session under his belt.
“I think a lot of players shall come back in the month of March. But when they come back, it is not so easy to decide if they can cope with the rhythm of a match because they are fit to train with us. For example, Schweinsteiger has only had one training session with us behind his back. Valencia has a week [behind him] so he is much closer to being on the bench, for example, but not to play a match as that’s different.
“I don’t think [any new players will be available] but Valencia is fit enough to be on the bench, but to play 90 minutes, I don’t think so.
“I shall always make my line-up in my eyes as the strongest line-up to play against the opponent. Nevertheless, I put youngsters sometimes in the line-up but then then I think it’s the best solution. I also have to cope with the busy schedule so sometimes I spare and rotate players because of that.”
Van Gaal’s small squad has been stretched to the limit as a result, but it has allowed young players such as Marcus Rashford and Timothy Fosu-Mensah to gain experience in the first team. While it has been good to see the youngsters make the step up, United undoubtedly need to add some depth to the squad in the summer.