Sources: Trilogy fight between Roman 'Chocolatito' Gonzalez and Juan Francisco Estrada called off due to COVID; Julio Cesar Martinez agrees to 115-pound bout with Gonzalez

Roman "Chocolatito" Gonzalez won't face Juan Francisco Estrada in a hotly anticipated trilogy fight after all.

Estrada withdrew from the bout after he became symptomatic with COVID, sources tell ESPN. In his place, 112-pound champion Julio Cesar Martinez has agreed to a deal for a 115-pound fight with Gonzalez on March 5 in San Diego, sources said.

Martinez (18-1, 14 KOs) is an explosive puncher who is trained by Eddy Reynoso at Canelo Alvarez's San Diego gym. The 26-year-old Mexican has competed at 115 pounds numerous times earlier in his career, most recently in March 2019.

One of the sport's most reliable action fighters, Martinez is ESPN's No. 1 flyweight, a champion since he scored a ninth-round TKO of Cristofer Rosales in December 2020. He made three successful defenses before his November meeting with McWilliams Arroyo resulted in a no contest due to a cut suffered by Martinez's opponent following a clash of heads.

They exchanged knockdowns in Round 1 before Martinez floored Arroyo again in the second. Now, Martinez prepares for the toughest challenge of his career.

Gonzalez (50-3, 41 KOs) is a future Hall of Famer who enjoyed a long reign as the consensus pound-for-pound best boxer in the world. The 34-year-old Nicaraguan is a four-division champion and is currently rated No. 2 by ESPN at 115 pounds.

"Chocolatito" dropped a controversial split decision to Estrada in March, a brutal battle that was ESPN's runner-up for fight of the year. They combined for 2,529 punches, a CompuBox record at 115 pounds.

The rematch came more than eight years -- and two weight classes -- after their first fight. When they met in 2008, Gonzalez won a unanimous decision to retain his 108-pound championship in another firefight.

Gonzalez now prepares for what shapes up as another scintillating matchup, even if it isn't the bout he yearned for all along. The third chapter with Estrada will have to wait.