Don't let his bashful smile fool you. Hunched over a chessboard, 15-year-old Hikaru Nakamura is one of the most ruthless competitors you'll ever see. "He goes right after the best guys in the game," says the U.S. Chess Federation's Tom Brownscombe. "In a world full of cautious chess players, Hikaru plays to win." A tennis-playing Tennessee Titans fan from White Plains, N.Y., Hikaru became the youngest U.S. grandmaster by scoring 7� points in 11 games at the Bermuda International Chess Festival. ( Bobby Fischer was four months, four days older when he became a grandmaster in 1958.) "This takes some pressure off," said Hikaru, who is homeschooled by his mother, Carolyn Weeramantry, and stepfather, Sunil Weeramantry, a renowned chess teacher. "I felt like I had been so close for a while." Nakamura picked up the game at age seven from his older brother, Asuka; by 10 he was the youngest U.S. master ever. He's always been aggressive, sacrificing pieces to earn technical advantage. "What amazes me is his willingness to try new systems in the most crucial situations," says Sunil, an international master. "Such fearlessness, it can't be taught."