The Dutchman sustained a groin injury that kept him out of the 4-1 derby humiliation against Manchester City on Sunday and has not trained this week.
Moyes said: "I don't think Robin will play [against Liverpool]. He will have an outside chance of playing on Saturday.
"It's always a big game when you play a cup game and Liverpool are our big rivals.
"Maybe this does take on more significance. Luis Suarez coming back means that Liverpool will have a really good player."