Peterborough invited old boy David Seaman back to London Road, but already relegated Wycombe, managed by the goalkeeping legend's former England and Arsenal team-mate Tony Adams spoiled the end of season party.
Seaman, who started his league career with Peterborough 22 years ago, saw Wycombe's Nathan Tyson grab a last second equaliser when he connected with Matt Bloomfield's swirling free-kick and sent the ball soaring into the roof of the net.
There wasn't even time for the game to be restarted and it was a frustrating finish for Posh who had looked on course for victory thanks to a 64th minute effort from player of the season Curtis Woodhouse.
The former Birmingham midfielder scored his seventh goal of the campaign with an unstoppable left-footed volley after connecting with a cross from Ryan Semple.
Tricky teenager Semple's work on the right was impressive and both Dave Farrell and Calum Willock went close from his early centres.
Wycombe managed to keep possession for long spells, but this tactic almost backfired when long-serving skipper Steve Brown lost out to Adam Newton who sent Farrell away to bring a brave save from on-loan Aston Villa goalkeeper Wayne Henderson.
"To concede a late goal yet again simply sums up our home form this season," said Posh boss Barry Fry.
He added: "We've done it too mane times and it has cost us dearly, but on the credit side I was impressed with the showings of youngsters Ryan Semple and Sean St Ledger who are great prospects for the future." Wycombe were most dangerous when Danny Senda was on the ball and his promptings created openings for Tyson and Mark Philo.
Over 400 Wycombe fans made the trip North and their backing touched manager Adams.
"The fans gave us great support during the game and stayed behind for half an hour to give the lads a standing ovation.
"If they give that much support when we are playing appallingly we will have to work to give them the success they deserve next season," said Adam.