Darmian was forced off during United’s 1-0 defeat by Southampton at Old Trafford last weekend but posted a positive injury update on social media following the game.
Van Gaal confirmed that Darmian would miss Friday’s fourth-round tie but is hoping to see the full-back return to action sooner rather than later.
Speaking to MUTV on Thursday, Van Gaal said: “It’s more or less the same.
“Darmian is now out and maybe Michael Carrick shall come in but of course he’s not able to play 90 minutes. But it’s very good he is coming back.
“With Darmian, it is very positive actually. It’s not too severe but he’s not able to play against Derby.”
The United boss also remained coy when quizzed about injured duo Bastian Schweinsteiger and Phil Jones ahead of Friday’s cup clash.
He continued: “I cannot say [if they are close] because every time I make a remark about injuries it is always difficult because injuries have developments and you have to wait and see.
“Also, they have to train and be adapted to the rhythm of the Premier League which is high. When you are more weeks injured it takes more time to adapt to that rhythm.”
Marcos Rojo, Luke Shaw, Antonio Valencia and Ashley Young are all still absent for Manchester United with long-term injuries.
United head into the game looking to return to winning ways after the disappointment of their 1-0 loss to the Saints last weekend.
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