Matthew Renshaw will be assessed ahead of day four's play in Sydney before being cleared to bat after the Australian was hit on the helmet while fielding.
The 20-year-old was struck while fielding at short leg on the third day against Pakistan as Sarfraz Ahmed played a delivery from Steve O'Keefe.
It was the second time Renshaw had taken a blow to the head in this Test after a bouncer from Mohammad Amir hit him on the grill on day one.
He left the field two overs after being struck on Thursday, complaining of a headache.
"With Matt Renshaw he'd come off with some headache," said assistant coach David Saker.
"He'll be assessed throughout the night and in the morning.
"These days with head knocks, you got to take them seriously. He'll be assessed and we'll deal with that in the morning. Hopefully he'll be fine."
Australia hold a commanding position in the Test with Pakistan reaching 271-8 at the close of play in reply to the hosts' first-innings total of 538-8 declared.