Marc Bridge-Wilkinson stuck out a foot deep into injury time to lift Port Vale to three precious Division Two points and shatter a ten-man Peterborough side that looked to have battled back to salvage a draw.
After just one win in their previous dozen outings manager Brian Horton has no doubt Bridge-Wilkinson's effort will be worth its weight in gold for Vale.
Horton said: "It was a vital victory but we have 21 games left and have to treat them as 21 cup finals if we are to make progress." Neither side sparkled in a poor first half when chances were negligible apart from a Posh break when Adam Newton headed against the inside of a Vale post and Liam Burns swept the rebound off the goal-line.
Ironically it was a wild clearance by Newton that put Vale on the road to victory in the second of three added minutes, the Posh man gifting the ball to Paul Byrne whose grateful swirling cross was met by Bridge-Wilkinson storming in at the far post.
Posh had been reduced to ten men just before the break when skipper Andy Edwards was cautioned for the second time in 15 minutes for separate fouls.
A reorganised defence held out until the 73rd minute when Steve Brooker put Vale in front beating keeper Lee Harrison from a tight angle.
The lead lasted just nine minutes until a piece of dazzling individual skill by Jimmy Bullard paved the way for a Posh equaliser.
The midfielder, currently being pursued by Nottingham Forest and Preston, turned the Vale defence inside out before slipping the ball for Newton to set up 35-year-old Andy Clarke for his 14th goal of the campaign.
Posh boss Barry Fry: "After equalising I thought that even with ten men we could on and win the game. But Adam Newton held up his hand to take full responsibility for the mistake that let Vale in and I admire him for that."