Gauteng-based rider Wesley Marwing suffered a suspected fractured clavicle when taking a tumble at Fairview on Friday.
Marwing replaced the stood down Robert Khathi and produced a late flying finish on the Jacques Strydom-trained King Of Seville, who stormed up at 50-1 for third behind Hawk Circle and Single File in the fifth race.
He fell just after they passed the post.
No other details are known at this stage.