TOKYO - Japanese boxing wonderboy Naoya Inoue dethroned Omar Narvaez of Argentina with a second-round knockout and grabbed the World Boxing Organization junior bantamweight title. The unbeaten 21-year-old previously captured the World Boxing Council light flyweight title in April and defended it in September.

For this match, Inoue jumped up two categories in what was touted as an ambitious shot to fight Narvaez, 39, who had defended the WBO belt for 12 years. But the Japanese fighter, nicknamed "Monster", was in control from the start of the bout, putting his experienced opponent to the floor three times, before finishing with a killer left body punch that kept Narvaez on his knees.

"I have practiced the body punch, and I thought I can bring him down if I could find opportunities to use it," Inoue said after the match. I appreciate this opportunity to fight the super champion (Narvaez) in Japan," he added. Inoue is undefeated -- his professional record now stands at eight wins, seven by knockout.

The bout was part of a triple header that also featured Mexican Pedro Guevara lifting the WBC light flyweight title by flooring Japanese fighter Akira Yaegashi. Guevara's seventh-round knockdown with a stunning body punch denied Yaegashi's attempt to win his third world title. Meanwhile, Jorge Linares of Venezuela won a WBC lightweight title by beating Mexico's Javier Prieto. Linares collected his third world title with his fourth-round knockout, after winning the WBC featherweight and the WBA super featherweight titles.