Simeon Jackson and Jon Aston were on target as Rushden eased their relegation worries at Forest Green. Jackson broke the deadlock after 48 minutes with his 15th goal of the season, heading home from Michael Rankine's cross.
And the visitors sealed their win - their first in five attempts - five minutes from time when Ashton powered home Curtis Woodhouse's cross.
For Forest Green, it was a defeat that pushed them closer to relegation.
Forest Green: Robinson, Hardiker, Jones, Giles, Nicholson, Lawless, Pitman (Afful 55), Brough, Clist, Dodgson (Stonehouse 54), Bertram (Preece 81).
Subs Not Used: Harrison, Lamb.
Rushden & D'monds: Tynan, Ashton, Albrighton, Hope, Watson, Williams, Mills, Woodhouse, Kelly, Rankine, Jackson (Tomlin 89).
Subs Not Used: Baker, Savage, Goodliffe, Bostwick.
Booked: Woodhouse, Watson, Albrighton.
Goals: Jackson 48, Ashton 85.
Att: 1,110
Ref: A Rodda (Yorkshire).