Germany's Christian Kukuk wins showjumping gold ahead of Switzerland's Guerdat
Swiss Steve Guerdat won silver with his horse Dynamix de Belheme. Dutch Maikel van der Vleuten with horse Beauville Z was third.
The blockbuster jump-off between the three was held on a shorter course than the initial final rides.
In the day's main shocker a little earlier, Sweden's showjumping star Henrik von Eckermann, the current world champion who was seen as one of the hottest contenders for gold, fell from his mount King Edward, resulting in his elimination.
The roughly 16,500 people of the Versailles arena held their breaths when the gelding started to falter midway through the course. Von Eckermann fell into the sand seconds later when the horse suddenly stopped.
The horse - the best on record according to analyst firm EquiRatings - did not fall, and Von Eckermann was seen walking out of the arena with no apparent signs of injury.
The 15 artfully designed obstacles reminiscent of Paris landmarks like the Arc de Triomphe and Eiffel Tower of up to 1.65 metres (5.41 ft), challenged riders and horses, with much fewer clear rides than in the qualifier on Monday.
As the hooves of all but three of the world's finest jumping horses knocked wood at least once during their rides, nervous sighs and frustrated 'aahs' shaped the ambient noise in the arena facing Louis XIV's world-famous Palace.
"It's a tough course but it's the Olympic final, that's what we expect,", defending Olympic champion Ben Maher from Britain said after he failed to reach the jumpoff. "It just wasn't meant to be today."
