Chris Elder scored with the final play of the game to give London Welsh victory over Jersey and end the islanders' four-month unbeaten run on home soil.
Tries from forwards Alex Woolford and Jesse Liston put Welsh 14-3 ahead at half time.
Nick Haining's try from close range and Brendan Cope's penalties helped pull Jersey level.
But a quick tap penalty and break away saw Elder go through for the winner.
It means the Exiles climb to seventh spot in the Championship table, while the islanders pick up a losing bonus point and remain fifth.
Jersey: Adair; Howe, Evans, Cooke, Lane; Cope, Fisilau; Lockwood, Selway, Kerrod, Phillips, Campbell, Rae (capt), Freeman, Haining.
Replacements: McCarthy, Garcia-Veiga, Herriott, Kolo'ofa'i, Spinks, Moates, Owen.
London Welsh: Jewell; Elder, Reynolds, Armitage, Drauniniu; Barkley, Glynn; Aholelei, Britton, Cooper, McNally, Woolford, Liston, Hodson, Thorpe (capt).
Replacements: Allen, Trevett, Gilding, Corker, Murphy, Lewis, Carlisle.