Halfbridled is a bay mare bred by in Kentucky by the French-based Wertheimer et Frère, who also owned her during her racing career.
She then won the Grade 2 Oak Leaf Stakes at Santa Anita Park, a prep for the Breeders' Cup World Championships.
[2][3] Entering the Breeders' Cup Juvenile Fillies undefeated, Halfbridled started as the 2-1 favorite in a field of fourteen.
[5] After the Beaumont Stakes, it was discovered that Halfbridled had sustained an injury to her canon bone and would be sidelined for the rest of the season.
The following November, after supposedly healing from her injury, Halfbridled returned to training to prepare for the 2005 racing season.