David Ball's early brace handed Peterborough a win and condemned Dagenham & Redbridge to the League One relegation places.
Craig Mackail-Smith, playing against his former club, played Ball in to slot past Tony Roberts after three minutes.
Ball, making only his third start of the season, made it 2-0 five minutes later with a smart finish after the ball fell kindly to him in the area.
Mackail-Smith hit the side netting and then fired wide in a quiet second half.
The Daggers now sit in 21st place in the table, one point below Notts County.
Peterborough manager Darren Ferguson told BBC Radio Cambridgeshire:
"The lads did everything I asked to the letter, as we knew they'd throw balls into the box and we dealt with it.
"David Ball has scored two really good finishes, it was a good performance and one we certainly needed.
"It sets us up for Huddersfield on Saturday, and everyone is looking forward to it as we know that if we beat them then we go above them."