"fan favorite all-time Thoroughbreds bracket challenge"

[Calzone Lord]

The Paulick Report is doing this. So far they have released the top 7 seeds.

1s: Secretariat, Zenyatta, Man O' War, Ruffian
2s: Cigar, Rachel Alexandra, Seattle Slew, Sunday Silence
3s: Affirmed, Forego, Barbaro, John Henry
4s: Kelso, Seabiscuit, Alydar, Dr.Fager
5s: Tiznow, Alysheba, Spectacular Bid, Smarty Jones
6s: Curlin, Holy Bull, Big Brown, Easy Goer
7s: Native Dancer, Black Caviar, Phar Lap, Personal Ensign

I'm surprised Afleet Alex and Funny Cide didn't make the list.