Japan's Koki Kameda retained his title against the Mexican bantamweight David De la Mora jury's unanimous decision (114-113, 115-113 and 115-112) on Wednesday.
"De La Mora is a young talented fighter. I'm very glad to fight with him." said Kameda, who was however disappointed with his fitness.
"Ihave to work harder. I do not know yet what my next fight but I will do better next time." he added.
De La Mora, seventh in the rankings of the WBA, was very aggressive throughout the fight and appeared to tire in the 12 rounds, while trying to fight Kameda.
In the third round, the Mexican released a flurry of jabs that did bleed the left eye of his rival, but the Japanese responded with a powerful left hook.
This is the second defenceof the Japanesechampion, who won the vacant title against the Venezuelan Alexander Munoz in December last year.
Kameda now has a balance of 26 wins (16 KOs) and one loss while De La Mora, 23, suffered his first defeat after winning his previous 23 fights, 16 of them before the bell.
Koki Kameda is the eldest of three fighters, known for their behavioral problems.
Daiki Kameda was suspended one year for foul play in a match against countryman Daisuke Naito in October 2007 while Koki was also fined for Japanese sports officials for inciting her brother to use these tactics.
His father, Shiro Kameda, who coached his sons, also had problems and was expelled from the World Boxing Council (WBC) for insulting the referee.