Chris Cunningham stood wearing a white apron behind the checkout counter at Schaller & Weber, a butcher shop on the Upper East Side, ringing up a mink-draped customer. Under the rim of his crisp paper cap, Mr. Cunningham’s brow was visibly swollen, yet his smile was quick and generous — both products from the previous night’s championship bout at an illegal boxing club in an industrial section of the Bronx.

Regulars at the traditional German deli, where Mr. Cunningham’s father is the store manager, are accustomed to the scrapes and bruises of Mr. Cunningham, a 22-year-old Filipino-American amateur boxer, who goes by the name Pacquiao in the ring. Beneath his apron and a Winnie-the-Pooh tie, he wore the championship prize he won the night before: a 32-inch, 14-karat gold chain that plunged past his sternum. “Here, man, check it out,” he said, handing the necklace to a visitor; its heft inspired a guffaw of happy disbelief. Mr. Cunningham and his co-workers were later amused when he placed the chain on the meat counter scale, weighing it in at more than half a pound.

Mr. Cunningham’s pleasure in the moment was obvious. What was probably less clear to the customers shopping in Yorkville was the long road he took to becoming the proud owner of the Cuban link-style championship chain. Since a humbling defeat early in a tournament last year, Mr. Cunningham intensified his training as he gradually advanced through the second competition, which began in October. He shadowboxed on the No. 7 train on his early-morning commutes; jogged in the slush along Queens Boulevard after his shifts at work; and in his mother’s backyard in Rego Park, he clobbered a makeshift stack of bald tires, a much cheaper training option than a heavy bag.

By the final round of the tournament, Mr. Cunningham had developed the physique of a prizefighter, though at 180 pounds, he is quite a bit heavier than Manny Pacquiao, the great Filipino welterweight champion and the source of his nickname.