Pakistan suffered a setback Thursday with pace bowler Khurram Shahzad ruled out of their series against Australia after pulling up sore following a heavy defeat in the first Test.
The 24-year-old impressed on his debut in Perth, finishing with match figures of 5-128, removing Steve Smith twice.
But he complained of discomfort and scans showed a stress fracture in the ribs along with an abdominal muscle tear.
"PCB will now consult a specialist in Australia after which a final management protocol will be established for the player," the Pakistan Cricket Board said in a statement.
"He will then return to Lahore, where he will continue his injury management and rehabilitation."
Pakistan already had a weakened bowling attack after speedster Naseem Shah was omitted from the tour due to a long-term injury.
Spinner Abrar Ahmed missed the Perth Test, which they lost by 360 runs, with leg discomfort, but could return for the second match in Melbourne that begins December 26.
Pakistan, who have not won a Test in Australia since 1995, have Hasan Ali and Mohammad Wasim in their squad as potential replacements for Shahzad.