The Breeders' Cup Championships return to Churchill Downs Friday and Saturday. The event features the world's top thoroughbreds competing for some $26 million in purses.Track spokesperson Darren Rogers says this is the first time for Churchill to host the event since it went to a two-day format, and there will be other races on the cards as well."All told, over the two day period, we'll have 14 Breeders Cup World Championship races. Six of the eleven races are for Breeders' Cup," he said. The highlight of the event will be the $5 million Breeders' Cup Championship on Saturday, when the undefeated mare Zenyatta will attempt a record breaking 20th straight victory.