South Africa and Pakistan both have concerns over their fast bowlers ahead of the first Test of a three-match series starting at Centurion Park on Thursday.
Pakistan, already with five fast bowlers in their squad, added a sixth in the controversial Shoaib Akhtar as cover for Umar Gul, who suffered with an ankle injury during the team's warm-up match against the Rest of South Africa at the weekend.
Shoaib, cleared by a Pakistan tribunal after being found guilty of using illegal substances - together with team-mate Mohammad Asif - was due to leave Pakistan on Tuesday and it will be a surprise if he plays in the first Test barely 24 hours after his arrival.
Gul, meanwhile, may still be considered.
While Pakistan contemplate their options, Shahid Nazir advanced a strong claim for inclusion by taking five wickets against the Rest of South Africa on a batsman-friendly pitch in Kimberley.
South Africa are expected to be without Dale Steyn, their fastest bowler, who is likely to be rested after playing a significant role in the host nation's come-from-behind win over India in Cape Town last Saturday.
Steyn missed the second Test against India because of a thigh strain and coach Mickey Arthur said he would probably sit out the Centurion match to give him time to make a full recovery.
Andre Nel is likely to be back in action after recovering from a heel injury.