Aaron McLean spearheaded a storming Peterborough revival as they came from a goal down to win.
The home side went behind when Paul Benson capped an incisive move by finishing smartly with the outside of his boot past keeper Mark Tyler.
But a Dean Keates goal started a Posh comeback before McLean grabbed two goals in the space of three minutes.
Former Daggers man Craig Mackail-Smith was the architect of both strikes and took McLean on to 11 goals this season.
Peterborough: Tyler, Gnakpa (Hyde 56), Morgan, Westwood, Day, Whelpdale, Lee, Keates, Boyd, Mclean, Mackail-Smith.
Subs Not Used: Jalal, Newton, Howe, Branston.
Goals: Keates 69, Mclean 79, 82.
Dag & Red: Roberts, Foster , Boardman, Smith, Griffiths, Graham (Taiwo 58), Southam, Huke, Sloma, Benson, Moore (Strevens 66).
Subs Not Used: Thompson, Rainford, Uddin.
Goals: Benson 30.
Ref: Steven Cook (Surrey).