LOUISVILLE, Ky. – If there is a Grade 1 race on dirt for older fillies and mares, it seems trainer Steve Asmussen has a horse primed for it. In April, Asmussen won the Apple Blossom at Oaklawn with Midnight Bisou. On Friday, he took the La Troienne at Churchill Downs with She’s a Julie. And Saturday on Kentucky Derby Day at Churchill, he added a third Grade 1 when Mia Mischief cruised to a 1 3/4-length victory over Marley’s Freedom in the $500,000 Humana Distaff. Mia Mischief’s victory was the biggest surprise of the trio in the view of the betting public, who let her slip to 11-1 odds following a second-place finish in the ungraded Carousel at Oaklawn on April 6. She was an improved horse Saturday, always well positioned. She laid in second off the pacesetting Amy’s Challenge through an opening quarter-mile of the seven-furlong Humana Distaff timed in 22.70 seconds, well in hand for jockey Ricardo Santana Jr. Then, as the field hit the turn, she began to dial up the pressure on the leader, and the pace quickened to 45.02 for the half mile. Amy’s Challenge then came under a ride by jockey Alex Canchari, but Mia Mischief was still moving comfortably, and once asked in the quarter-mile stretch, the rout was on. Mia Mischief surged to a 2 1/2-length lead with an eighth of a mile remaining and was never threatened by Marley’s Freedom, who rallied belatedly. “Not enough can be said about how good Ricardo has done with her,” Asmussen said of Santana’s ride. “The filly is very headstrong, very difficult. And he gave her a dream trip, and he’s definitely done his part.” The Humana Distaff marked Mia Mischief’s second major graded stakes triumph at Churchill Downs, coming a year after she won the Grade 2 Eight Belles on the Kentucky Oaks undercard. She raced seven furlongs on a fast track in the Humana Distaff in 1:21.78, paying $25. “This week, going seven-eighths of a mile, obviously suits her,” Asmussen said. Saturday’s victory gave Mia Mischief, a 4-year-old daughter of Into Mischief, the first Grade 1 triumph of her career and improved her record to six wins from 14 starts for owners William and Corrine Heiligbrodt, Heider Family Stables, and Madaket Stables. The 9-10 public choice, Marley’s Freedom, the winner of the Grade 1 Ballerina last summer at Saratoga, closed strongest Saturday, though jockey Mike Smith said she was not at her best over the Churchill Downs surface, where she had run fourth as the favorite in the Breeders’ Cup Filly and Mare Sprint last fall. “She hates this track,” he said. “She won’t even warm up over it.” Lasting for third, four lengths behind Marley’s Freedom, was Amy’s Challenge. She was followed by Spiced Perfection, Emboldened, Spring in the Wind, and Talk Veuve to Me.