Japan's Shinsuke Yamanaka knocked out Jose Nieves of Puerto Rico with a lightning straight left in the first round to retain his World Boxing Council bantamweight title in Tokyo on Monday.

It was undefeated Yamanaka's fourth defence of the title, which he won in 2011 by an 11th-round technical knockout of Mexico's Christian Esquivel.

Left-handed Yamanaka went out fighting from the opening bell, taking on the number-eight WBC contender with both hands.

After two minutes, Yamanaka had his challenger in a corner and connected a straight left to the face.

The Puerto Rican fell down and referee Bruce McTavish counted him out with 20 seconds left in the round.

"I may sound arrogant but I honestly really wanted to fight a little more," the 30-year-old champion said before a roaring crowd at the Ota gymnasium.

"I wanted to show a little more to the crowd."

Yamanaka's record improved to 19 wins, 14 of them by knockout, and two draws.

For Nieves, 32, it was his third loss against 22 wins, 11 of them inside the distance, and three draws.

"It didn't carry much steam but I fell probably because it was a good punch," the Puerto Rican said of the straight left that sank him. "I couldn't see it coming so I guess it had speed."