Daily Racing Form reports that jockey Javier Castellano has chosen to ride Algorithms, giving up the mount on Union Rags, in the Grade 2 Fountain of Youth at Gulfstream Park on February 26. Union Rags will pick up the services of Julien Leparoux.

"Javier rides five top (Kentucky) Derby prospects, four of which are with one trainer," Castellano's agent Matt Muzikar told DRF, referring to Algorithms and his Todd Pletcher-trained stablemates Discreet Dancer, El Padrino and Gemologist.

"This was a very tough decision, but Javier and I thought it was the right decision."

Castellano guided Union Rags to impressive victories in last year's Grade 1 Champagne and Grade 2 Saratoga Special for owner Phyllis Wyeth, whose nom de course is Chadds Ford Stable, and trainer Michael Matz. Last time out, Castellano and Union Rags suffered a tough loss to Hansen in the Breeders' Cup Juvenile, where the colt lost his perfect record, and a championship.

Castellano has been aboard Starlight Racing's unbeaten Algorithms in all three of his starts, including his smashing win over Hansen in the Grade 3 Holy Bull at Gulfstream on January 29.

Algorithms will be trying two turns for the first time in the 1 1/16-mile Fountain of Youth, which marks the sophomore debut for Union Rags.

"Both of us have the utmost respect for both Michael Matz and Mrs. Wyeth," Muzikar said. "They are both very classy people, and we wish all the connections of Union Rags the best."

Leparoux was quick to express his enthusiasm for his new mount.

"I'm so excited about the news, can't wait to ride Union Rags," Leparoux tweeted, adding a :) for effect.