Auguy Slowik's stoppage-time try saw Jersey Reds become the first side to beat London Irish in the Championship this season as they came from behind to win 17-14 at St Peter.
Topsy Ojo's converted try for Irish produced the only first-half points.
Slowik pulled a score back soon after the half-time break, but Blair Cowan went over to put Irish 14-5 up.
Leroy Van Dam crossed to reduced the deficit four minutes later before the late winner.
The victory moves the islanders up to third place in the Championship after a sixth successive win, while Irish remain four points clear of Ealing at the top.
Irish, who were relegated from the Premiership last season, had won their first eight games of the season, seven with bonus points.