William J. Lombardy, who was one of the most talented and promising chess players of his generation, winning titles and accolades while he was still a teenager, but who all but gave up the game at the height of his career to become a priest, died on Friday in Martinez, Calif. He was 79.

His son, Raymond, confirmed the death. He added that the sheriff’s department in Contra Costa told him that Mr. Lombardy, who was born in the Bronx and had long lived in New York City, died of natural causes, probably heart disease, while staying with a friend in Martinez.

Mr. Lombardy was the first American to win the World Junior Chess Championship — doing so with a perfect score, a feat that has never been duplicated — and he led the United States to victory over the Soviet Union in the 1960 World Student Team Championship, beating Boris Spassky, the future world champion. He was later named a grandmaster, the World Chess Federation’s highest title.

“His abilities were native, with a natural talent,” Anthony Saidy, an international master who played with Mr. Lombardy on the 1960 team that won the Student Chess Olympiad, told The New York Times in 2016. “He always seemed to drag his matches out so long, getting out of jams until his opponent couldn’t.”