Devon's push for a place in the County Championship final suffered a setback on Saturday as they lost to Gloucestershire at the Brickfields.
After a tight first half, which ended with Gloucestershire holding an 8-3 advantage, the visitors took charge.
Converted tries from Tom Jarvis and Dan Hodge, with a Tim Stevenson penalty put Gloucestershire out of reach.
Devon now have to win at Hertfordshire next weekend and rely on Cornwall beating Gloucestershire to go through.
All of Devon's points came from the boot of fly-half Dan Mugford, who kicked three penalties.
Gloucestershire's other scorers were Jack Preece, who claimed a first-half try, and Chris Ashwin, whose early penalty opened the scoring.
The win means Gloucestershire now sit top of South Division One, having beaten both Devon and Hertfordshire.