AFC Wimbledon moved five points clear of the Sky Bet League One relegation zone and dealt a fresh blow to Peterborough's play-offs hopes with a 1-0 win at Kingsmeadow.
Joe Pigott scored his fourth goal in five games to extend Posh's winless run to six games and leave them four points off the final play-off spot.
Although Peterborough enjoyed more first-half possession, Christy Pym was the busier goalkeeper as he denied Anthony Hartigan and Mitch Pinnock.
Pym continued to frustrate the hosts after the restart, tipping over Mads Sorensen's header and thwarting Pigott with a low save.
But the Dons were finally rewarded in the 58th minute when Pigott fired past Pym on the turn.
Ricky-Jade Jones then saw his goal-bound effort hooked onto the post by Luke O'Neill and Ivan Toney hit the side-netting on the rebound.
Posh pushed for an equaliser, with Sam Szmodics and Toney going close, but their troubles in front of goal continued as they failed to score for the fifth time in six league games.