Macclesfield are awaiting the results of a scan on Nat Brown's leg injury, which they are calling "a weird one".
The defender limped out of Saturday's FA Cup draw against Southend but an X-ray on Monday came back clear.
"It's a bit of a weird one," said manager Gary Simpson.
"It's something that's causing Nat's leg to lock up which clearly isn't ideal when you are trying to run around a football field.
"The X-ray hasn't revealed anything so he's in for a scan and hopefully that can give us a better idea."