Midfielder Goran Lovre suffered whiplash after being knocked out in Barnsley's clash against Crystal Palace on Saturday.
The 28-year-old Serbian was left unconscious after being struck by a shot from Palace midfielder Darren Ambrose late in the Tykes' 1-0 win.
Lovre was later discharged from hospital after X-rays revealed no serious damage, but Barnsley manager Mark Robins has revealed they are monitoring the injury.
"We'll have to wait and see how he is," Robins told Barnsley's official website.
"Gorna has a whiplash-type injury and will definitely miss training on Monday."