Uncertainty over the fitness of world's top test bowler Dale Steyn has seen selectors add Morris while de Kock's inclusion suggests that AB de Villiers might not be required to keep wickets again and will instead be allowed to concentrate on his batting.
De Villiers had returned with the gloves behind the wickets for the first test in Durban to allow South Africa to add an extra batsman in their line-up but the team scored 214 and 174 in their two innings.
Steyn suffered a shoulder spasm in the second innings and his absence was keenly felt as the home team lost by 241 runs to England.
South Africa had originally named a 13-man squad for the first two tests because of the quick turnaround between the matches.
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"Following our performance and injuries in the first Test, we have recognised the need to bolster the squad," said Linda Zondi, Cricket South Africa's convener of selectors.
"This will provide us with more selection options for the second Test match at Newlands."
Squad: Hashim Amla (captain), Kyle Abbott, Temba Bavuma, Quinton de Kock, AB de Villiers, JP Duminy, Faf du Plessis, Dean Elgar, Morne Morkel, Chris Morris, Dane Piedt, Kagiso Rabada, Rilee Rossouw, Dale Steyn, Stiaan van Zyl
(Editing by Sudipto Ganguly; mark.gleeson@thomsonreuters.com; +27828257807; Reuters Messaging: Reuters Messaging: mark.gleeson.thomsonreuters.com@reuters.net)
