A 32-year-old man suffered head injuries and a suspected broken nose at Norfolk Christian Football Youth League's five-a-side tournament.
The games feature 33 youth teams from churches across the country and players pray before matches.
The competition covers a selection of age groups from under tens to under 16's, as well as adult levels.
Chairperson of the league, Michael Culwick, told the Daily Telegraph: "The police were called immediately and took charge of the situation, allowing the tournament to continue.
"The welfare and protection of young people are extremely important in our league, and this is the first serious incident that we have had since the youth league was founded 21 years ago.
"We deeply regret that this took place, but we are determined to continue this valuable ministry which has tremendous support from all those involved in the league."
The alleged victim was taken for treatment to the Norfolk and Norwich University Hospital.
A 32-year-old man has been arrested on suspicion of assault causing actual bodily harm.
He was released on police bail until June 20th.
