Guernsey FC conceded three second-half goals as they were beaten 3-1 at Footes Lane by Badshot Lea.
Matt Loaring's close-range effort put Guernsey in front after 24 minutes.
George Hedley levelled from close range early in the second half before Loaring hit the bar with 20 minutes left.
But Badshot went straight up the other end and scored as Reece Robins lobbed the onrushing Josh Addison before Robins got a second late on as he converted after his penalty was saved.
Guernsey felt they should have had a penalty soon after Badshot's second goal when Jack Griffin went down under a challenge, while at the other end Addison did well to save an effort from Lamin Ceesay.
Guernsey's bad day was ended when Loaring hit the bar for a second time in the final minute.
The loss leaves Guernsey in the bottom third of the Isthmian League South Central Division with one win and four losses from their opening five matches.