The mixed martial arts world on Tuesday mourned the loss of popular Japanese fighter Norifumi "Kid" Yamamoto, who died after a battle with cancer at age 41.

Competing mostly as a lightweight and sometimes as a featherweight, Yamamoto had 18 wins, six losses and two no contests during a 14-year career including stints in the Ultimate Fighting Championship and the Japan-based K-1 promotion.

(Norifumi "Kid" Yamamoto in January 2007)

The youngest son of a famous wrestling family, Yamamoto enjoyed huge popularity in his home country at the height of his MMA career.

His father Ikuei wrestled for Japan at the 1972 Munich Olympics, while his younger sister Seiko was a four-time world champion. His older sister, Miyu, won three world titles.

In 2007, Yamamoto retired from MMA in a bid to wrestle for Japan at the 2008 Beijing Olympic Games. But his attempt to make the team ended after he suffered a dislocated shoulder during the qualifying tournament.

Yamamoto announced he had been diagnosed with cancer and was fighting the disease in an Instagram post on Aug. 18. His gym confirmed he had died while undergoing treatment on Tuesday.

UFC Hall of Fame inductees Ken Shamrock and BJ Penn were among a number of mixed martial arts luminaries to express their condolences.

In a Twitter post, Shamrock called Yamamoto "a true legend of the sport."

"My thoughts are with his family and worldwide fans as we reflect on an amazing person and athlete," he tweeted.

Former UFC lightweight and welterweight champion Penn said he was "absolutely devastated by this news."

"MMA has lost a true legend," he said.

UFC president Dana White also took to social media to express his sorrow, tweeting, "RIP...Norifumi "Kid" Yamamoto."