Guernsey narrowly beat Jersey by nine runs in the final over at the ICC World Cricket League Division Six.
Guernsey won the toss and batting first made 251-8, helped largely by 80 from all-rounder Jeremy Frith.
In response Jersey openers Dean Morrison and Ed Farley put on 131 for the first wicket on a thundery day in Malaysia.
Despite scoring 19 runs from the 44th over, Jersey were dismissed with four balls remaining.
Guernsey skipper Stuart Le Prevost said: "Credit to the Jersey guys they put up a great fight.
"We possibly could have got a few more runs but we would have taken that score at the start.
"It's always important to get a win in the first game."
The top two teams in the tournament will be promoted to Division Five.
Chris Minty, chief executive of the Jersey Cricket Board, said: "The boys worked very hard in the field to hold Guernsey to 251 on a good batting pitch.
"Some missed chances early on proved to be costly however."