Vidic was forced out of their win over Arsenal at halftime yesterday.
Moyes gave a positive update on the fitness of Vidic and explained the 32-year-old will now undergo a scan.
"I didn't see the incident at first," Moyes said. "From the touchline, I thought it was just a clash but I've had a chance to see it now and he took a terrible blow. But as far as I know, he is okay. He is conscious, he will get a scan and we hope he will be okay."
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