Fast bowler Anrich Nortje has a shoulder injury.
The pitch has helped the chasing teams going by the recent records at the venue.
Mohammad Hafeez is expected to be fit for the last match.
Pakistan won their only T20I at the venue by 95 runs back in 2013.
Steyn picked up two wickets in that game.
Pollock also posted a tweet later.
Amla played until the very end and guided the Proteas through to the triumph.
India are third on the list.
Steyn is currently playing South Africa's opening Test against Pakistan in Centurion.
Steyn became the Proteas' leading wicket-taker in Test cricket.