CAPE TOWN: South Africa have added uncapped opener Stephen Cook to their squad for the final test against England in Pretoria starting on Friday in a bid to bolster their brittle top order. The 33-year-old has enjoyed an excellent season in the domestic four-day competition with 415 runs in six innings at an average of 83, including two centuries. South Africa have battled with their top six batsman over the past year and in the last three months have been bowled out for their two lowest scores since returning to international cricket in 1991 -- 79 in India and 83 by England on Saturday. The right-handed Cook is the son of former test opener Jimmy Cook who played in three test matches in the twilight of his career following South Africa's return to the global game. The Lions batsman, who is expected to replace the woefully out-of-form Stiaan van Zyl, was the only change to the squad from the one that lost to England by seven wickets at the Wanderers to surrender the four-match series. It was reported on Monday that Dale Steyn will again miss out in Centurion with a shoulder injury despite lengthy treatment in a hyperbaric chamber in a bid to get him ready. The fast bowler will work towards being fit for the five-match one-day international series starting on February 3. Wicketkeeper Quinton de Kock will also be assessed to see if he has recovered the knee injury sustained while walking his dog on the eve of the Wanderers test. If he does not, Dane Vilas will retain his place in the side. South Africa test squad: AB de Villiers (captain), Kyle Abbott, Hashim Amla, Temba Bavuma, Stephen Cook, Quinton de Kock, JP Duminy, Faf du Plessis, Dean Elgar, Morne Morkel, Chris Morris, Dane Piedt, Kagiso Rabada, Rilee Rossouw, Dale Steyn, Stiaan van Zyl, Hardus Viljoen.