Showtime has announced that 2012 Olympian Terrell Gausha will face Charles Whittaker in a junior middleweight fight to open tonight's Showtime Extreme card from the StubHub Center in Carson, Calif., in place of what should have featured unbeaten junior welterweight Antonio Orozco against Martin Honorio.

The postponement was due to "visa issues" for Honorio, of Mexico, according to Golden Boy Promotions Vice President and matchmaker Eric Gomez.

Earlier, Showtime had announced that a junior featherweight bout between 2012 U.S. Olympian Joseph "Jo Jo" Diaz (9-0, 7 knockouts) and Luis Maldonado (36-12-1, 27 KOs) was to replace Orozco-Honorio before making the adjustment for a more competitive co-feature, according to Showtime Sports publicist Chris DeBlasio.

The 26-year-old Gausha (8-0, 5 KOs) was last in the ring for unanimous decision over George Sosa in February, and Whittaker (40-14-2, 24 KOs), who turned 40 in January, was last in action for a fourth-round knockout of Juan Manuel Matias in October.

In the main event, junior middleweight Jermall Charlo (17-0, 13 knockouts), twin brother of 154-pounder Jermell Charlo (23-0, 11 KOs), will be after his 12th consecutive knockout victory against Hector Munoz (22-12-1, 14 KOs) and, time-permitting, Brazilian 2012 Olympian Yamaguchi Falcao will be televised starting at 7 p.m. ET/PT.

Charlo was last in the ring for a fifth-round stoppage of Joseph De los Santos in December while Munoz, 35, was knocked out in the third round by Ronald Cruz in November and has lost three of his past four fights. Charlo was slated to face IBF titleholder Carlos Molina last month until Molina was arrested five days prior to the fight, which was canceled.

Falcao will fight Carlos Badaldua, the latter of whom will be in his pro debut. Falcao will be in his second pro fight, having been involved in a ruled no-contest in January after he and rival Martin Fidel Rios (11-0-2, 5 KOs) were mutually disqualified for repeated fouls.

The three bouts are part of an undercard that will precede the Showtime tripleheader headlined by welterweight Keith Thurman against Julio Diaz and supported by RING number one-rated junior welterweight Lucas Matthysse versus John Molina and WBC lightweight titleholder Omar Figueroa Jr. opposite Jerry Belmontes.

The Thurman-Diaz card will follow the 9:30 p.m., ET/6 p.m., PT broadcast of the second of four 30-minute episodes of All Access: Mayweather vs. Maidana in advance of Floyd Mayweather Jr.'s May 3 defense of his RING and WBC welterweight championships against WBA counterpart Marcos Maidana on Showtime Pay-Per-View from the MGM Grand in Las Vegas.

Orozco-Honorio could land on a May 15 Golden Boy Live! show on Fox Sports 1, according to an earlier report by ESPN.com.

Nicknamed,"Relentless," the 26-year-old Orozco (19-0, 15 KOs) was to be after his eighth consecutive stoppage win against the 34-year-old Honorio (32-8-1, 16 KOs), a former title challenger who has lost his past two fights by majority and unanimous decision to former titleholder Juan Carlos Salgado and Argenis Mendez in April and July 2012, respectively. Orozco was last in the ring for January's second-round knockout of Miguel Angel Huerta.