Having surged four clear on Thursday, Sergio Garcia's progress was checked by a difficult day at the Nedbank Golf Challenge.
Sybi Kuchar joined Matt Kuchar on the course on Thursday, caddying for Zach Johnson as her husband enjoyed a fine round.
Sergio Garcia made a brilliant start as he eyes back-to-back titles, shooting his lowest round in Sun City for 17 years.
Rory McIlroy will go second in the Race to Dubai standings behind Francesco Molinari if he wins in Sun City this weekend.
DeChambeau held off a charging Patrick Cantlay to win in Las Vegas.
Olympic champion Justin Rose returned to world number one on Sunday after triumphing at the Turkish Airlines Open.
Li Haotong's putter erred at the crucial moment to hand Justin Rose the Turkish Airlines Open title and a return to world number one.
Bryson DeChambeau and Peter Uihlein share the lead after the third round of the Shriners Hospitals for Children Open.
Li Haotong leads the Turkish Airlines Open with 18 holes left thanks in part on an incredible eagle at the 10th.
Peter Uihlein has never won on the PGA Tour.