Pakistan accumulated 259-5 on the opening day of the second and final Test in Rawalpindi.
Poor catching from South Africa helped Pakistan, with five catches dropped on a turning pitch.
Pakistan punished poor catching from South Africa to accumulate 259-5.
Saud Shakeel and Salman Agha will resume on Tuesday unbeaten on 42 and 10, respectively.
Pakistan seeks a 2-0 series win against the world Test champions.
Author's summary: Pakistan leads with 259-5 on the first day.