Tjaart van der Walt joins Louis Oosthuzen at the top of the Africa Open leaderboard . Choi carded 70 . Veteran South African cards 18 - under par to join major winner on 21 under par . Former European Tour No . 1 Retief David is a shot behind going into final round . Defending champion Chris Byrd claims a two - shot lead at PGA Tour 's final event .
Tjaart van der Walt joins Louis Oosthuzen at the top of the Africa Open leaderboard . Veteran South African cards 18 - under par to join major winner on 21 under par . Former European Tour No . 1 Retief David is a shot behind going into final round . Defending champion Chris Byrd claims a two - shot lead at PGA Tour 's final event .