Winger Richard Haughton has left Jersey for French Top 14 side Perpignan after just one match for the islanders.
The former Wasps and Saracens player joined Jersey as one of 10 summer signings ahead of the club's first season in the Championship.
But a clause in his contract allowed him to consider approaches from "top level clubs".
Haughton, 31, will move to Perpignan on an initial six-month deal as cover for injured full-back Sofiane Guitoune.
"We're disappointed, but a player like Richard, who has played club rugby at the top level, was likely to attract interest of this kind," said Jersey director of rugby Ben Harvey.
"We can't compete financially with a club the size of Perpignan.
"We've enjoyed having Richard in the squad for the past two months, other players have learned a lot from him and he will go with our best wishes."
Haughton's only match for Jersey was the
pre-season friendly defeat by Leicester Tigers earlier in August.
His departure comes just days before the island side's first ever match in the second tier of English rugby, against Cornish Pirates on Saturday.