Former welterweight world titleholder Luis Collazo suffered a torn calf muscle in training, forcing him to withdraw on Friday from his fight against rising contender Sammy Vasquez.

Collazo and Vasquez were due to meet in a 10-round bout on July 16 (Fox, 8 p.m. ET) at Legacy Arena in Birmingham, Alabama, in the opener of the Premier Boxing Champions card headlined by Deontay Wilder's heavyweight world title defense against Chris Arreola.

Luis Collazo (tan/blue/red trunks) suffered a torn calf muscle in training, forcing him to withdraw from his scheduled fight against rising contender Sammy Vasquez. Ed Mulholland/USA TODAY Sports

Vasquez will remain on the show and face a new opponent, contender Felix Diaz, the 2008 Dominican Olympic gold medalist, PBC announced.

"Sammy Vasquez Jr., a U.S. Army veteran and undefeated contender, against once-beaten former Olympic Gold medalist Felix Diaz is an excellent matchup between two rising stars in the welterweight division," promoter Lou DiBella said. "Following last week's tremendous battle between [Keith] Thurman and [Shawn] Porter, I am excited that PBC on FOX is showcasing the welterweight division once again on network television."

Diaz, 32, is coming off his first defeat, a highly debatable decision loss to former junior welterweight titlist Lamont Peterson in October.

The 30-year-old Vasquez (21-0, 15 KOs), a native of Monessen, Pennsylvania, who served two tours of duty in Iraq as a member of the U.S. National Guard, is coming off a sixth-round knockout of Aron Martinez on Jan. 23.

Diaz will be the most notable opponent of his career, as Collazo (36-7, 19 KOs) also would have been. But at least the change in opponents won't force Vasquez to change much in his training -- both Diaz and Collazo are left-handed.

Diaz (17-1, 8 KOs) had been scheduled to face Levan Ghvamichava (16-2-1, 12 KOs), of the Republic of Georgia, in the main event of a PBC card on July 12 (Fox Sports 1/Fox Deportes, 11 p.m. ET) at Robinson Rancheria Resort and Casino in Nice, California. PBC announced that Ghvamichava, 30, will now face Domonique Dolton (17-0-1, 9 KOs), 26, of Detroit, in a junior middleweight bout that will headline the July 12 card.