Japan's Kazuto Ioka fended off a strong challenge from Juan Hernandez of Mexico by a unanimous decision to defend his World Boxing Council strawweight title on Wednesday.

The three judges counted it 116-112, 114-111 and 118-111 in favor of the defending champion.

"He (Hernandez) was a strong fighter, stronger than I had expected. I wanted to win by a knockout, but I must want for my next chance. I want to become stronger," said Ioka, 22.

"I know I will have tough fights in my following defence of the title. I just want to fight one by one," he added.

Hernandez, ranked top in the WBC, came out aggressively from the off and frequently making capital with his powerful left hook.

Ioka retaliated with a one-two combination starting with a jab and connected with a right straight in his opponent's face at the end of the second round.

The Japanese led 39-37, 39-38, 39-37 after four rounds but took a left hook in the fifth round.

Hernandez began to look more passive after his nose started bleeding in the seventh round and he was down 78-74, 78-74, 79-74 after the eighth.

Knowing he needed to floor his opponent to win, Hernandez went for the knockout but Ioka fought back, pummeling the Mexican's torso.

Although Ioka cut his right eyelid in the 11th round, he connected his right straights and hit Hernandez's stomach several times in the last two rounds to end the fight.

It was Ioka's first defence of the title he wrested from Oleydong Sithsamerchai of Thailand in February, stretching his unbeaten record to eight wins, including five KOs.

The 24-year-old Mexican, who hadn't been beaten in the past five years, saw his record reduced to 18 wins, including 13 KOs, against two defeats.