Bideford slipped up 32-26 in a high-scoring Western Counties West encounter at Chard.
Will Copp scooted in for a try hat-trick, and Alex Priest crossed too, as Bideford shot into a 26-6 lead with 20 minutes to go.
That should have been a winning position, but it proved to be otherwise.
Back came Chard and three tries in the final 10 minutes took them to what seemed like an unlikely win.
Simon Morrell, the Bideford coach, said: "We were magnificent for 60 minutes.
"Will Copp, Callum Davies, Alex Priest and Oliver Sanders led the team superbly well, taking the game to Chard.
"Our ability to manage the conditions, mix-up our kicking game and impose ourselves on Chard physically was fantastic, as was our maul.
"Unfortunately at 26-6, we switched off and Chard found a foothold in the game through their powerful set piece.
"Three tries in the last ten minutes gave Chard a deserved late win.
"We have no complaints and can be very proud of our performances these past few weeks.
"We are most certainly getting better and look forward to a big end to the season."
Barnstaple are now two games behind schedule in the South West Premier after another unplanned day off.
Barum were due to visit Bracknell on Saturday, but that game was called off due to waterlogged surface.
It was the second week in a row that Barnstaple had a Saturday afternoon off. Seven days earlier they were due to visit Weston before the weather intervened.
Barnstaple are still top of the table though as results elsewhere did them a favour.
Maidenhead would have gone past Barum had they won at University of Exeter, but the Students held them to a 20-all draw.
Barnstaple resume league fixtures on January 4 when Brixham visit Pottington Road. The Weston game has been re-arranged for January 25 and the trip to Bracknell is pencilled in for February 22.
Barnstaple and Bideford will clash at Pottington Road on Boxing Day in the traditional Christmas derby.
As Bideford play two divisions below Barnstaple, they will start as underdogs.
But Barnstaple may well rest some of their players to keep them fresh for the return to league rugby in early January.
And don't be surprised to see a couple of trialists from local club don the red shirt either.
Kick-off time at Pottington is 2pm. Admission is a fiver for adults. Under 18s will be admitted free.
South Molton were forced to cancel their trip to Penzance to face Pirates Amateurs due to a shortage of players.
Molton were down to a bare 15 available players on Friday evening - and some of them were either poorly or injured.
Reece Eury, the South Molton captain, said it was a reluctant but necessary decision to pull out.
"When the fixtures came out we knew then it would be tough getting a side out for an three-hour coach ride on the Saturday before Christmas," said Eury.
"You get the feeling not a lot of thought went into compiling the fixtures for Christmas week."
South Molton, now 17 points adrift at the bottom of the Cornwall and Devon table, have no game until Plymstock Albion Oaks visit Unicorn Park on January 4.
Torrington and Ilfracombe had no games on Saturday.