More than 1000 young footballers will swamp Sunnyvale for the annual Green Island seven-a-side tournament tomorrow.

The tournament has been running for more than 40 years and attracts teams from around the region.

While teams from Oamaru and Gore are not taking part this year, there are still 121 teams entered, including some from Balclutha.

Green Island Junior Football Club president Peter Cromb said the tournament's success stemmed from the rare opportunity for the juniors, aged from 6 to 13, to play for something.

''I think it's the element of competition,'' he said.

''In the tournament they've got something to go for. In the Saturday competition they don't have tables or ladders or anything like that. I think they see the FA Cup on TV and that kind of thing, so it's just something to aim for.''

This year's entry list matches last year's total, but is down from the record number (140) in 2013.

However, the tournament continued to be popular because of the ''huge number'' of children playing football in Otago, Cromb said.

The tournament is open for boys and girls, with mixed teams featuring in addition to teams solely made up of boys or girls.

Action gets under way at 9am and should finish by 4pm.

The tournament will be held next Sunday if it is too wet tomorrow.