The Ecuador international has been out of action for a number of months due to injury but is now closing in on a return and has been training with the United first-team for the past week.
Van Gaal also revealed that midfielder Bastian Schweinsteiger has been training with his side in recent days but said that the Germany international is not likely to be fit to face Liverpool at Anfield on Thursday.
Speaking at his pre-match news conference at Carrington on Wednesday morning, Van Gaal said: “Valencia is coming back, Schweinsteiger is coming back.
“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 the match because they are fit to train with us but, for example, Schweinsteiger has only one training session with us, and Valencia has a week.
“Valencia is much closer to being on the bench, for example, but not to play a match. That’s different.”
United head into the game looking to return to winning ways after the disappointment of their 1-0 loss to West Brom at the weekend.
The Red Devils have won their last four Premier League fixtures against Liverpool since a humiliating 3-0 home defeat in March 2014.
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