A late goal from central defender Michael Duff salvaged a precious point for Cheltenham Town and edged them a step closer to possible Division Two safety.
The Robins' cause was further helped by defeats for Huddersfield Town and Chesterfield, their two main rivals in the dogfight, and it appears that the outcome will not now be settled until the final weekend of the season.
Peterborough, who had secured their own Second Division survival with a run of three consecutive wins, appeared content to sit back and let Cheltenham come at them for most of the game.
This the Robins duly did and a succession of half chances came and went with on-loan striker Marvin Brown putting the best two of them either side of goalkeeper Mark Tyler's posts.
The home side appeared nervous, the tension from their supporters being transmitted onto the pitch, and their worst fears were realised in the 64th minute when Posh took the lead.
Gareth Jelleyman's long throw from the left was flicked on by Jason Lee and Andy Clarke turned sharply in the box before rolling a shot past Shane Higgs.
That goal came rather against the run of play although with Cheltenham comitting more and more men to attack the chances began to arrive for Posh.
Higgs made good saves from Clarke and Adam Newton but veteran Cheltenham substitute Tony Naylor almost scored when his clever lob shot rebounded back off the crossbar.
A frantic end to the game saw Cheltenham boss Bobby Gould throwing four up front and one of them, defender Duff, came up with the equaliser four minutes from time.
He latched onto a pass from Russell Milton and strode through a gap in the defence before beating Tyler with a low shot off the post.
"We were apprehensive and it was not a good performance from us," said Gould.
"But the lads have shown that they will not give up. We threw everything at it and got a reward in the end." Peterborough manager Barry Fry said: "I'm going away from here livid because we should have won the game.
"We had enough chances to make the three points safe, but credit to Cheltenham who kept going right until the end."