The sides play at KGV on Saturday at 11am and 3pm, before the final game at Port Soif on Sunday at noon.
The Sarnians have named their 14-man squad, which includes teenagers Charlie Forshaw, Ollie Clapham and Charlie Birch.
Guernsey squad: Luke Bichard, Charlie Birch, Martin-Dale Bradley, Ollie Clapham, Zak Damarell, Ollie Nightingale (c) , Ben Ferbrache, Ben Fitchet, Charlie Forshaw, Harry Johnson, Adam Martel, Dane Mullen, Tom Nightingale, Matt Stokes.