"Sami has been complaining of back pain since the series started. Though he has braved it so far, he is in more pain since Friday," Pakistan coach Javed Miandad said on Saturday.
"He is getting treatment and there is still time before the match. So, we remain hopeful."In case Sami is ruled out of the match, the hosts will have just one regular paceman in Shoaib Akhtar.
Besides Shabbir Ahmed, Pakistan's hero of the Lahore Test Umar Gul has also been ruled out of the third Test with a back injury.
Shabbir, suffering from shin injury, missed the second Test along with allrounder Abdul Razzaq (back) and wicketkeeper Moin Khan (groin strain).
Pakistan have included four pace bowlers - Fazl-e-Akbar, Abdul Rauf, Rana Naved-ul-Hasan and Rao Iftikhar - in a 17-member squad named on Friday for the final Test.
Miandad sought to put up a brave front saying "Injuries are a big problem. But I have confidence in the ability of our back-up bowlers to give the Indians a hard time. We believe we still have the bowling strength to bowl them out."