Grouville inflicted a first league defeat of the season on Jersey Scottish as they beat the runaway Premiership leaders 3-1 at Springfield.
Island players Russell le Feuvre and Craig Northedge did the damage in four first-half minutes.
Le Feuvre blasted in from three yards out after Scottish failed to clear a 24th minute corner before Northedge headed in a free-kick from close range.
Steve McCarter's own goal made it 3-0 before Jack Boyle got one back late on.
Scottish are still 10 points clear at the top of the table but have now played one game more than second-placed St Peter.
The win lifts Grouville up to third place, 13 points off the Scots with two games in hand.