Thailand's Ratanachai Sor Vorapin is apparently good enough to beat opponents with only one good hand.

Vorapin, the WBO world bantamweight champion, defeated Pedro Malco Jr. of the Philippines in a 10-round unanimous decision last night in the main event of a professional boxing card at the Blaisdell Center Arena. A crowd of around 500 watched Vorapin improve to 65-8-1, although his world title was not on the line.

Vorapin fought with an unorthodox style throughout the bout, and at times, appeared to be toying with Malco. But after the fight, Vorapin said it was part of an unexpected strategy.

"I hurt my (left) hand in the first round, so I started to play around," he said. "I had to protect my hand and I couldn't punch hard."

Malco landed his share of punches throughout the bout, although he never appeared to hurt Vorapin. There were no knockdowns in the bout.

"He was really tough," Vorapin said of Malco. "I was having a hard time knocking him out."

Malco dropped to 13-11-3. Both fighters weighed 121 pounds.

In the semi-main event, Waipahu's Dustin Kim lost a bout and then announced his retirement.

Thailand's Kosol Sor Vorapin, who is Ratanachai's younger brother, won a six-round unanimous decision over Kim in a 129-pound bout. Vorapin knocked Kim to the canvas twice in the third round, and then dominated the fight after that.

"I fought a good fight, but a guy like this, if I'm going to go anywhere, I'm supposed to beat him," Kim said. "I was in shape as far as conditioning, but sometimes when you don't have it, you don't have it in the ring."

Kim dropped to 19-7 with his second loss in Hawai'i this year. Kosol improved to 9-9-1.

"It's time for me," said Kim, 31. "I had a good career. I think I made it pretty far — 19-7 is not that bad."

In other preliminary bouts: