AFC Rushden & Diamonds suffered a setback in their attempts to seal a play-off place when they lost 2-1 at Chasetown.
The battle for a spot in the extended Evo-Stik Northern Premier League Division One South season is increasingly tight with a half a dozen sides still in contention.
So defeat at Chasetown, who started the night in 17th place, is a huge disappointment for Andy Peaks men.
The home side took the lead when Ryan Wynter scored after 13 minutes.
In the second half Nabil Shariff levelled for Diamonds from the spot after a defender had handled.
But, despite creating plenty of chances, the visitors could not score again and it was Chasetown who bagged the decisive goal when Jack Langston struck with 15 minutes remaining.