Former Olympic gold medalist Felix Diaz (17-1, 8 knockouts) will face Sammy Vasquez (21-0, 15 KOs) on July 16 in the co-feature of a PBC on Fox card after former titleholder Luis Collazo pulled out with a calf injury, a source confirmed to RingTV.com on Friday. The date is headlined by WBC heavyweight champion Deontay Wilder’s voluntary defense against two-time title challenger Chris Arreola from Legacy Arena in Birmingham, Alabama.

Diaz, who won gold for the Dominican Republic at the 2008 Olympics, had been penciled in to face Levan Ghvamichava on a PBC on Fox telecast on July 12. He will be moved to face Vasquez in what on paper shapes up to be a more competitive match-up. Diaz, a southpaw, lost a controversial majority decision to former titleholder Lamont Peterson last October in a bout many observers thought he won. Now, he will provide Vasquez, who served two tours of duty in Iraq as a member of the national guard, perhaps his stiffest test to date.

Collazo, a former titleholder, had a preexisting calf injury and tweaked it in training this past week, a second source said. In his last fight, Collazo hurt welterweight titleholder Keith Thurman with a body shot before he succumbed to a cut and quit after the seventh round last July. He will heal up and hope to get another big-fight opportunity.