Simsri, The Ring's No. 3-rated junior flyweight, is well versed on what to expect from his tough Mexican opponent but believes he'll have more than enough to emerge victorious.

"In his 27 fights, he's undefeated," Simsri (39-1, 13 KOs) told The Ring. "He's definitely a great boxer, but I have no worries, because I always do my best in every fight. It might be a pretty dangerous match, but I have confidence in my experience, my team, and my preparation, because I never underestimate my opponent in any fight.

"Mendoza is a skilled boxer with powerful punches, but I believe I can stop him as well."

The two will meet on neutral turf at the famed Korakuen Hall in Tokyo, on a Ohashi Promotions show.

Simsri has fought overseas on several occasions. Mendoza will be fighting outside his homeland for the first time.

"That might be an advantage for me," he said. "I've competed in Japan a lot, and this is his first time competing abroad. But I won't underestimate him for a second."

The 25-year-old from Thailand hopes to put the division on notice with a win.

"Of course, I want to be champion in every organization," he said. "But I have to get through this fight first."

Simsri's manager Ookami Tora has known him for many years. He believes that now his fighter is a world champion, he won't give it up easily.

"We won't be complacent, and we definitely won't give up," the manager said.

"We never thought of ourselves as world champions, but we only thought that we are the real deal. We will never stop developing. There are so many talented people in the world, so we need to practice even harder."

Mendoza (27-0, 23 KOs), who is unranked by The Ring, has been a professional since 2018.

The 25-year-old southpaw from Hermosillo holds notable wins over Angel Ramos (KO 3), Joel Cordova (UD 10) and, most recently a third-round knockout of Mpumelelo Tshabalala in their IBF title eliminator on November 22.