Unbridled Danz, winner of the Audubon Stakes at Ellis Park last year, sold for $510,000 as a broodmare prospect Monday early during the opening session of the Keeneland Janaury horses of all ages sale in Lexington. Dennis Yokum purchased the 4-year-old daughter of Unbridled's Song for Ernie Moody's Mercedes Stable. She will be bred to Rock Hard Ten, a grade I winner who was raced by Mercedes and Madeline Pickens."She's just a gorgeous mare; her conformation is excellent," said Yokum, who is the racing manager for Mercedes. "I think she is the type you want to breed to Rock Hard Ten. She matches up physically with him very well. She's not too big, but she's not small. I don't think you want to breed too big of a mare to Rock Hard Ten because he's already big enough."Greenfield Farm, agent, consigned Unbridled Danz, who is out of the Canadian stakes-winning Danzatore mare Chartreuse and is from the family of grade I winner Manistique (by Unbridled's Song's sire, Unbridled). Unbridled Danz raced for Stan Fulton.