Jersey Reds moved to within one point of opponents Cornish Pirates with a determined win at the Mennaye Field.
In a scoreless first half, Jersey's Jordan Davies came closest to a try but was held up just before the line.
The visitors did go ahead when prop Sean McCarthy went over after a series of pick and goes, and Callum Sheedy crucially kicked the conversion.
Kyle Moyle got to Max Bodilly's chip to touch down for the Pirates, but Will Cargill's kick was caught in the wind.
A losing bonus point keeps fifth-placed Pirates ahead of Jersey in the Championship table, but defeat damages the Cornish side's play-off hopes and ended their seven-game home winning streak.
The teams will meet again in the last eight of the British & Irish Cup at St Peter on Friday night.
Pirates coach Alan Paver told BBC Radio Cornwall:
"They deserved their victory - we couldn't get a grip of the game.
"Our normally potent kicking game didn't function, our line-out just couldn't give us enough possession and when we had possession we just couldn't keep it for long enough.
"It wasn't a spectacle of a game - in fact it was awful - but credit is due to them. They've come here and ground out a victory."
Jersey Reds head coach Harvey Biljon:
"Let's be honest, the rugby you saw is not what you want to see from the Pirates or Jersey.
"Anything could've happened, and it was difficult for rugby players out there.
"Around the 60-minute mark we probably had a sustained period of pressure and I think we should've come away with more, but ultimately we'll take the win on what was a very difficult day."
Cornish Pirates: May, O'Meara, Bodilly, Hendrickson, Moyle, May, Day, Walker, Innard, Andrew, Parker, Caulfield, Cheesman, Stevens, Duncan (capt).
Replacements: Andrew, Chapman, Lee, Bartlett, Pope, Cargill, De Battista.
Jersey Reds: Cuthbert; Adair, Davies, Ma'afu, Scott, Sheedy, Hardy; McCarthy, Buckle, Tampin, Phillips, Voss, Freeman (capt), Graham, Haining.
Replacements: Macfarlane, Woolmore, Armstrong, Kolo'ofa'i, Argyle, Dudley, Robling.
Referee: Simon Harding.
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