Wath-upon-Dearne fell nine points behind third-placed Doncaster Phoenix in the Yorkshire One table, after a 17-11 defeat at Bridlington.
Wath, who prevailed 49-21 back at Moor Road in the last meeting between the two sides in October, started well, and they went ahead thanks to an early try by second row forward Gareth Webb.
Bridlington, who beat Phoenix the week before this clash, drew level with a try from their winger Will Davies.
Soon after, a penalty goal from full-back Tom Quinn put Wath back in front at 8-5.
The next try was always going to be crucial, and it was Bridlington who got it just before the half time whistle when second-rower Auryn Murray went over.
Jamie Muru converted to put Bridlington 12-8 ahead at the break.
Quinn’s second penalty proved to be Wath’s only score of the second half, and Bridlington sealed their win when prop Ezra Luxton crashed over for a try in the last minute of the game.
Muru missed the difficult conversion kick, which handed Wath a bonus for losing by seven points or less.
Elsewhere, Phoenix were forced to settle for a losing bonus point as they were edged out 10-9 at league leaders Dinnington.
The home side took the lead in the first half, scoring a pushover try on 20 minutes.
Ben Millar struck three quick-fire penalty kicks after the break to give Phoenix a 9-5 lead.
But Dinnington pinched the win in the last play of the game, once more scoring a try from a pushover in the corner.
Wheatley Hills battled to the narrowest of wins over Sheffield RUFC, running out 13-12 winners in their North One East clash.