England's Ben Stokes will have a scan on Monday after he injured his shoulder on the first day of the third Test against Pakistan.
The all-rounder, 24, left the field with his arm in a sling after a diving attempt to take a catch in Sharjah.
Stokes was fielding at backward square leg when he dived in a bid to catch Sarfraz Ahmed off bowler Samit Patel.
"As soon as he hit the ground we knew he was in trouble," England pace bowler Stuart Broad told BBC Sport.
"It's a worry, but we have strength in batting and bowling to cover if he can't play a further part."
He was in obvious discomfort as he lay face down and, after receiving treatment, left the pitch using his shirt as a makeshift sling.
"No one likes to see a player get injured and we know how tough Stokesy is," added Broad. "It takes a lot for him to show pain."
Stokes left the field midway through the evening session of a day where England bowled Pakistan out for 234 then reached 4-0 at the close.
"I shouldn't think he's fit to bowl, and there's huge question mark over whether he will bat," former England batsman Geoffrey Boycott told BBC Test Match Special.
England trail 1-0 after two Tests and need victory in the final match in Sharjah to avoid a series defeat.
Stokes is not part of the squad for the four one-day internationals and three Twenty20 internationals which follow the Tests.