The tournament will be the first test run for the new changing rooms in the south-west corner of the park.
The new building is the latest stage in the park's development. Other upcoming projects include an 80-space car park off Dynes Rd, which will be installed over the next six months, and an eight-court indoor facility due to open in winter next year.
The project will transform the Rolleston park, giving sports teams and the public access to new high quality facilities.
Said Selwyn District Council major projects’ manager John Reid: "The use of the fields at the south-western corner of Foster Park required a changing room and public toilets to get the best use out of them.
"It increases access for the public to use that space, and it will make a big difference for sports like rugby in the winter and softball and touch in the summer to have somewhere they can use for tournaments, regular weekend competition and training."
It also has six public toilets, which will be open 24 hours a day, and two baby changing facilities.
The district council is also working on the relocation of the Rolleston Rugby Club clubrooms from Rolleston Reserve to Foster Park.