Yamanaka overpowered his opponent in the late rounds on Friday night at Tokyo International Forum for a unanimous decision win in his first defense of the title he won by beating Mexico’s Christian Esquivel in November 2011.
The judges scored the bout 117-111, 116-112, 116-112 all in favor of Yamanaka, who improved to 16-0-2 with 11 knockouts. Darchinyan dropped to 37-5-1 with 27 KOs.
“It pretty much went according to plan,” the 29-year-old Yamanaka said. “I was able to land some good punches and take the momentum from him as the bout went on.”
HyeFighter Darchinyan dominated the early rounds but Yamanaka opened a cut over his opponent’s right eye with a left in the fifth round and the challenger never recovered.
Yamanaka staggered Darchinyan with another left in the 11th round. Darchinyan desperately attempted a comeback in the final round but was unable to cause any damage to the champion who had plenty of energy left.