John Velazquez will replace Julien Leparoux aboard Union Rags in the $1 million Belmont Stakes.

"We felt we had to make a change," trainer Michael Matz told Daily Racing Form. "What happened before, in the last two races, it can happen to any one of them. He doesn't look like he's difficult to ride. He does have a big, long stride, and you need to let him use that stride."

Leparoux gained the mount when Javier Castellano opted to ride Algorithms, who was subsequently injured, in the Grade 2 Fountain of Youth Stakes, guiding Union Rags to a four-length victory in his 2012 debut. But little went right for the Dixie Union colt in his next two outings, with Leparoux receiving plenty of criticism for his tactics following a less-than-ideal trip that resulted in a third-place finish in the Grade 1 Florida Derby next out.

Bet down as the 5-1 second choice in the Kentucky Derby, Union Rags experienced a dreadful journey as he was squeezed at the start and shuffled toward the back of the pack during the early stages. He continued to be plagued by traffic woes during the race and wound up a disappointing seventh.

Owned by Phyllis Wyeth, Union Rags skipped the Preakness in order to focus upon the last leg of the Triple Crown. Four of the last six Belmont winners have won off a similar five-week freshening.

Matz said he will continue to use Leparoux on his horses in the future.

"He understands," Matz said. "There's a lot of money at stake. Whether it was his fault or the horse's fault, it just didn't work out."