Imagine Manchester United playing Arsenal without a referee. And when the game's over, the score is forgotten, no points are awarded, and both start the next game without a league position.
This is the winning formula for the fastest growing team sport in the country, according to the Football Association of Sheffield. "Girls just want to play," says Julie Callaghan, the Sheffield FA's Girls' and Women's Development Officer, as 16 footballers in shin pads and ponytails expertly pass the ball through the drizzle in front of her.
And more of them want to play every day. With more than 60,000 registered players, and an estimated 1.4 million girls playing football at least once a week, football is now the most popular girls' sport in the country.
The problem for Julie was how to help hundreds of Sheffield primary girls play their favourite sport when pitches are scarce and many teachers are at a loss to understand the basics of the game, never mind the offside rule.
"Many female teachers had no experience of the rules at all, and they panicked," says Julie Callaghan. "But initially we said all you need to do is turn up, and the kids will play."
After several years of providing one-off girls' football tournaments over a single day, the pressure from players was getting so strong Julie decided a special primary league was needed for Sheffield's girls.
Girls could join their school teams along with their male classmates, but a special "fair play" league just for girls was seen as the best approach to encourage the maximum number of girls into the sport.
Schools were invited to register a team of eight Year 5 or 6 girls and then choose one of four sites around the city at which to play their matches (selected for their all-weather pitches, showers, changing facilities and security). It was free, with the local FA and the venues meeting the bill.
The "fair play" nature of the league means that the players referee the game themselves, says Julie. "They know when they've committed a foul and if there's a dispute a member of staff makes the final decision. It is easier to do with girls' teams than boys. It's all to do with their attitude," she says.
The other key component of the league was that there were no league tables.
"A lot of schools were at different levels of development," Julie says. "Some had been playing football for six weeks and some had been playing since Year 4, and we didn't want schools to get thumped in their first game and not want to come back.
"So every school started every game with a clean sheet, and in time teams who lost heavily started to draw and then win, and it was always exciting for them. We gained rather than lost support from the kids."
Interested schools were invited to the venue before matches to go through everything from child protection to basic rules and parking facilities, says Julie.
Schools are able to draw on resources and coaching programmes - kits, footballs, cones, bibs and coaching packs - can all be supplied from sources including the TOP scheme run by the Youth Sport Trust and the Football Foundation. In Sheffield, every school entering the league was given a place on a level one football coaching course, a policy in operation in many other areas around the country, says Julie Callaghan.
The Sheffield FA has also helped set up girls' club leagues, and schools will be able to liaise with their local girls' clubs through the PESSCL scheme (PE School Sport Club Links).
Richard Hallet, girls team coach and teacher at Westways Primary School, says: "I do think the structure of the league is necessary to encourage girls. Some of the boys think it's unfair that we have a team just for girls, but I think there are still fewer opportunities for girls to play football, so they need their own separate league."
The school's experience mirrors national interest in the game: in the year the girls' league has been in operation, the Westways squad has grown from eight to 15 girls.
"Girls absolutely love the game," says Jo Foster from Sacred Heart Primary School. As a teacher, Jo approves of the policy to have no accumulation of points, although she says her girls were slightly disappointed not to be able to follow their league table progress. "We have to work hard to keep up with their enthusiasm for the game," she says. "In the past we haven't been able to get enough matches."
The league has answered that problem for the moment, but Julie Callaghan is already under pressure to extend the Sheffield girls' league and more and more schools are already signing up for next season. "I think we're at the start of something huge," says Jo Foster.
A coaching conference is to be held at the South Leeds Stadium for women coaches of girls' football teams on September 11, pound;10.
Details from Julie Callaghan
Tel: 07770 857154
FA girls' football programme
Tel: 0845 310 8555 www.thefa.com