While the number of people playing the game overseas is still modest, the players’ enthusiasm is strong. Most are amateurs or semiprofessionals who compete on university teams or in leagues that have sprouted up. While some players are students, many others hold day jobs. Most of them play in front of meager crowds.

“Soccer is in our blood, but sometimes you need something more,” said Danilo Muller Ribeiro, the coach of the Brazilian team, which is competing in the tournament for the first time. “We’re doing this for the younger generation.”

Despite the anonymity and lack of money, a few players play well into their 40s.

“This is something I really like doing, so I keep training year by year,” said Yasuo Wakisaka, a 46-year-old defensive lineman who plays for the Panasonic Impulse, a company team in Japan’s X League. “I want to figure out the offense’s schemes and how to defend them. It keeps me going.”

Wakisaka, who is called Uncle Waki by some of his teammates, has a unique perspective on international football because he is the only player to take part in all five of the quadrennial world championships, starting with the inaugural event in 1999 in Palermo, Italy.

Although the tournament is being contested in the birthplace of the N.F.L. this year, it had an international flair. The seven teams marched behind flag-bearers in the opening ceremony. At the coin toss before the first game, the Australian captains gave their South Korean counterparts an inflatable yellow kangaroo with boxing gloves.

The teams stay and practice at Walsh University, about five miles from the stadium. For nearly two weeks, the leafy campus is turned into something approximating an Olympic village. The players and coaches rub shoulders each morning at breakfast, where some dine on kimchi and noodles brought from home. Many others eagerly fill their trays with college cafeteria mainstays like scrambled eggs, waffles and Froot Loops.