Conway will miss the match, starting in Wellington on Thursday, after hurting his thumb in a Twenty20 defeat to Australia last Friday in Auckland. New Zealand went on to lose the T20 series 3-0.
Williamson added that New Zealand, who have never won a Test series against South Africa, will focus on playing their brand of cricket to gain crucial WTC points.
Conway will miss the match, starting in Wellington on Thursday, after hurting his thumb in a Twenty20 defeat to Australia last Friday in Auckland. New Zealand went on to lose the T20 series 3-0.
Williamson added that New Zealand, who have never won a Test series against South Africa, will focus on playing their brand of cricket to gain crucial WTC points.