Following the opening ceremony at midday, hosts St John's face Raetia.
Then this evening Sealand take on Tamil Eelam.
The other teams involved are Alderney and Occitania.
There are three days of group matches, with finals day taking place on Sunday.
The tournament has attracted international media attention from the likes of the New York Times, CNN and even a Russian sports magazine.
Much of that is down to the involvement of Tamil Eelam, a side which represents the Tamil people.
They've called for an independent state to be set up for them in the north and the east of Sri Lanka.
The Tamil Tigers, a separatist militant group, fought a bloody 26-year civil war against the Sri Lankan government, before being defeated in 2009.
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