Pakistan captain Sarfraz Ahmed has been taken to hospital and did not take the field on day four of the second Test against Australia after taking a blow to the helmet, while visiting batsman Usman Khawaja was ruled out with a knee injury.
Sarfraz was on 33 in Pakistan's second innings on Wednesday in Abu Dhabi when a Peter Siddle bouncer struck his helmet.
The wicketkeeper brushed off the knock as he went on to make 81 off 123 balls, helping the hosts set a mammoth target of 538.
Asad Shafiq will lead Pakistan in his absence, while Mohammad Rizwan took the wicketkeeping gloves.
Australia were also dealt a major blow when it was confirmed that in-form opener Khawaja suffered a meniscal tear to his left knee that is likely to require surgery.
Khawaja, who has scored a match-saving 141 in the first Test, is now a doubt for the start of the home series against India, which begins in Adelaide on December 6.
