The League One trapdoor creaked open another notch as Carlisle’s away-day blues continued with defeat number 13 on the road in an increasingly morale sapping season.
Impressive Peterborough made it four home wins in a row to all-but secure the last play-off place, but the Cumbrians have it all to do as the gap to safety extended to three points with just three left to play.
Boss Graham Kavanagh made no less than five changes for the latest in what seems to have been a long line of ‘must-win’ fixtures, former Rangers veteran Nacho Novo called up to make his debut with loan striker Gary Madine unavailable due to the terms of his prison release licence.
Posh called the shots from the off and should have scored just three minutes in, Lloyd Isgrove skipping clear to cross low. Conor Washington showed neat control but lost his balance and dragged a tame shot wide.
Dangerman Isgrove then had a shot on the run and JOrdan Pickford had to drop low to beat it away.
The home side made the pressure tell just before the quarter hour when Josh McQuoid and Isgrove caused yet more problems out wide. A slip from Symington left space for the cross and Washington made no mistake with a sweet first-time volley.
Peterborough continued to boss things and Reece Brown was twice Carlisle’s hero with vital interventions, including a goalline clearance.
But ten minutes into the second half referee David Phillips awarded a controversial penalty, a cross appearing to hit Reece Brown in the midriff but the ref blew for a spot-kick, which Britt Assombalonga swept home.
Carlisle clawed their way back into it when Lee Miller grabbed his eighth of the season with a clinical volley.
But Posh’s two-goal cushion was restored, Assombalonga once more from the spot after having his heels clipped in the Carlisle area.
It was all hands to the pumps for Carlisle but a 90th-minute deflected finish from Michael Bostwick summed up their luck.