Julio Cesar Martinez is going on the defensive yet again…

The 25-year-old Mexican professional boxer and WBC flyweight world titleholder will defend his belt against Francisco Rodriguez Jr. on the Canelo Alvarez–Callum Smith undercard on December 19 at the Alamodome in San Antonio.

Martinez (17-1, 13 KOs) won the title in a ninth-round TKO victory over Cristofer Rosales in December 2019. He defended the belt twice this year, a unanimous decision victory against Jay Harris in February and a second-round TKO of Moises Calleros in October.

Martinez, who lost his pro debut in 2015, has gone 17-0 with one no-contest since then. He’s trained by Eddy Reynoso, who also trains Alvarez.

Rodriguez Jr. (33-4-1, 24 KOs) is a former strawweight world titlist. After losing back-to-back decisions against Donnie Nietes and Moises Fuentes in 2015, Rodriguez, 27, has won 14 straight bouts, 12 by stoppage.

Also on the undercard, super middleweight blue-chip prospect Diego Pacheco (10-0, 8 KOs) will face Rodolfo Gomez Jr. (14-4-1, 10 KOs) in an eight-round battle.