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.

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.