Rather than bring their own horses, athletes are randomly assigned a horse 20 minutes before they're set to compete.
The trouble started almost immediately. Shearwater Oscar didn't take kindly to a new face, bucking and neighing at the outset.
And when his new rider both refused to get off, and then accidentally guided him into one of the obstacles, that was that .
Each athlete has an official page on the London 2012 website. Some athletes have bios that run thousands of words (Michael Phelps and Usain Bolt, for instance). Others have scant information. The only nugget that appears in Hwang's bio: "Nickname is 'Careless' [because he makes many small mistakes]." Having his horse step on a flower pot probably qualifies as a small mistake.
Shearwater Oscar had decided enough was enough and bucked Hwang off the saddle. Fortunately, neither horse nor rider were injured.
Fair play to Hwang, though: he picked himself up and brushed himself off while Shearwater Oscar trotted away, then got back on and finished the job.
Hwang finished with 734 out of 1200 points in the riding, and ended up 34th out of the 36th competitors.
Eurosport / Chris Chase, Yahoo! Sports