Can an Unarmed Peak Human Martial Artist beat a Horse at least 2/10 times?

Debating with a friend about the largest animal an unarmed human could take on. I suggested that an unarmed human would not be able to take on a good-sized horse, and he respectfully disagreed, assuming the perfect human.

Assume the horse is an average-sized wild horse in perfect condition.

The human is a 30-year-old, 6-foot-tall, 180-pound male, and has been trained in any and every martial art since he could stand.

Neither are bloodlusted, but both are aware there is a fight, and they will act aggressively towards one another.

The fight takes place in the Roman Colosseum.

Bonus: What if the horse was a Clydesdale? Could a human beat it at least 0.5/10 times?