Rachel Alexandra, ridden by Calvin Borel, headed a field of six in her first appearance at Churchill since she set a record in the Kentucky Oaks last year, The Horse reported. It was her fifth loss in 16 starts.
Unrivaled Belle, with Kent Desmoreaux aboard and trained by Bill Mott, advanced four-wide on the second turn and made good in the final few jumps to finish the 1 1/16 miles on a fast track in 1:42.97. Morena was third, five lengths back.
Unrivaled Belle, a 4-year-old daughter of Unbridled's Song out of Queenie Belle, was fresh from a March 20 Rampart Stakes win and brought her earnings to $524,929.
Unrivaled Belle paid $20.80, $3.40 and $2.80; Rachel Alexandra, $2.10 and $2.10; and Morena, $4.80.