Sheffield saw their title dream dented after slipping to a shock home defeat in the first leg of their play-off quarter-final last night.
The Tigers produced a perfect start with a hat-trick of 5-1s in the opening three races, but they allowed Peterborough to mount a stirring comeback to take control of the tie.
Captain Jason Garrity picked himself up off the deck to earn the hosts the perfect start when following in Josh Bates for a 5-1 in the re-run.
Reserves pair Robin Aspegren and Paco Castagna quickly followed suit with a maximum of their own in heat two and Tigers were in dreamland when David Bellego led home Nicolai Klindt to complete the hat-trick in heat three.
But any thoughts of a cakewalk were quickly dispelled as Panthers found their feet before mounting a marvellous revival inspired by 18-point maximum man Ben Barker.
The visitors went from a dozen points down to two ahead in the space 10 races.
They provided a hat-trick of winners in shared races before slamming in a first 5-1 of their own in heat seven when guest Jonas B. Andersen and Michael Palm Toft left Andre Compton trailing in their wake.
The away successes continued as Emil Grondal took the flag in heat eight before Barker completed a hat-trick of triumphs in heat nine.
Bates gave the Owlerton faithful something to shout about when streaking clear in heat 10, but captain Garrity could not recover from an awkward moment going into the opening bend and brought up the rear.
Panthers ate into their arrears when the brilliant Barker led in Simon Lambert for a 5-1 in heat 11 and the same pair produced a valuable 4-2 in heat 13 before the turnaround was completed when Grondal and Palm Toft both roared past Aspegren in the penultimate race.
And that’s the way it stayed as star-of-the-show Barker completed his full-house in the finale to leave Tigers with it all to do at the East of England Showground later this month.
SHEFFIELD: David Bellego 11+1, Josh Bates 9+1, Jason Garrity 8+1, Robin Aspegren 7+1, Nicolai Klindt 4+3, Andre Compton 3+1, Paco Castagna 2+1.
PETERBOROUGH: Ben Barker 18 (max), Jonas Andersen 8+1, Emil Grondal 8, Simon Lambert 6+1, Michael Palm Toft 5+3, Rafal Konopka 1, Rider replacement for Ulrich Ostergaard.