HOLBROOK, N.Y., June 5  Victor M. De Leon III has been playing video games on the professional circuit for five years now, racking up thousands of dollars in prizes and endorsements at tournaments around the country. He has a national corporate sponsor, a publicist and a Web site, with 531 photos chronicling his career. A documentary filmmaker has been following him for months.

Victor weighs 56 pounds and likes to watch SpongeBob SquarePants at his home here on Long Island. He celebrated his 9th birthday last month with a trip to a carnival and a vanilla cake. He gets above-average marks in the third grade, where he recently drew a dragon for art class.

The appropriately named Victor  better known to cyber rivals and fans as Lil’ Poison  is thought to be the world’s youngest professional gamer; Guinness has called about listing him in its book of World Records. Starting on Friday, he is set to be among 2,500 competitors in the three-day Major League Gaming Pro Circuit Event at the Meadowlands in New Jersey, battling for titles like the titan on the Xbox game Halo 2 and prizes up to $20,000.

Asked what he thinks about the fuss over his virtual exploits, Victor shrugged with shy indifference. Pressed, he mumbled: “I don’t know. I didn’t think about it.”