ARCADIA, Calif. - Jockey Umberto Rispoli won the first Grade 1 race of his career in the United States aboard Rock Your World in the $750,000 Runhappy Santa Anita Derby on April 3. It turned out to be a temporary partnership. Trainer John Sadler informed Rispoli on Saturday that Rock Your World will be ridden by Joel Rosario in the $3 million Kentucky Derby at Churchill Downs on May 1. Rosario rode the undefeated Rock Your World to a win in a maiden special weight race on turf in January. Rispoli rode Rock Your World to stakes wins in the Pasadena Stakes at a mile on turf on Feb. 27 and the colt’s lone start on dirt in the Santa Anita Derby. “It was not in my hands,” Rispoli said during morning training Sunday. :: Bet horse racing on DRF Bets. Double Your First Deposit Up to $250. Join Now. “I was blessed to be on the horse in the Santa Anita Derby. It will be tough to see him going in the Kentucky Derby without me on his back.” Rispoli expressed concern that he may run out of time to find a Kentucky Derby mount. “I wish we had known earlier,” he said. “It would give us a better opportunity to find something else.” Rock Your World, owned by Pete and Kosta Hronis and Michael Talla, is rated as a leading contender for the Kentucky Derby. Sadler described the decision to change riders as “never easy.” Sadler said the recent defection of Concert Tour from the list of Kentucky Derby hopefuls triggered the decision to change riders. Concert Tour, trained by Bob Baffert, finished a quiet third with Rosario aboard in the Arkansas Derby at Oaklawn Park on April 10, the colt’s first loss in four starts. Rosario was aboard Concert Tour in all of those races, including stakes wins in February and March. Rosario and Sadler have teamed to win 242 races together in the last 15 years. This year, Rosario has won six races from 28 mounts on Sadler-trained runners. Rosario was away from California on the days of the Pasadena Stakes and Santa Anita Derby. On Feb. 27, Rosario rode at Oaklawn Park, where he rode a stakes winner. By April 3, Rosario had relocated to Keeneland for the spring. Rosario won four graded stakes at Keeneland that day. Rosario has ridden in the Kentucky Derby nine times, and won the race in 2013 with Orb. Rispoli, a native of Italy, began riding in the United States in late 2019, having relocated from Hong Kong. The Santa Anita Derby is his biggest win in the United States. Through Saturday, Rispoli ranked third in the jockey standings at the Santa Anita winter-spring meeting. Earlier on Saturday’s program, Rispoli and Sadler teamed to win the Mizdirection Stakes on Constantia, their eighth win from 21 mounts at the current meeting, which began on Dec. 26. “He’s doing well for me,” Sadler said. “He’s an up-and-coming rider and he’ll have more opportunities on our circuit. It’s not an easy situation.”