>>534933959
How zero is zero? It's incest city. Thoroughbreds always have been an eugenics program, 95% of them are descended from Eclipse and if your horse isn't then they're still a descendant of the three stallions, look up Notnowcato who won the Eclipse Stakes (heh) among others while being a Byrley Turk descendant instead of the much more dominant Arabian line.
Races talked about here are generally restricted to thoroughbreds as well, you need to look to history and open races where other breeds like arabians and quarter horses have beaten them in some cases, usually on distances and tracks where they hold the advantage.
https://www.horsenation.com/2023/02/24/the-greatest-match-race-ever-run/
There's a movie based on the above.