Sheffield found the loss of skipper Simon Stead just too much as they were edged out (45-48) in a Heat 15 decider at Owlerton.
Premier League Riders’ Champions Craig Cook and Ulrich Ostergaard carded a fifth successive 4-2 in the finale to hand Peterborough a win as the otherwise outstanding Dimitri Berge and Kyle Howarth were unable to respond.
But the damage had been done as early as Heat 3 when Stead, who had won his opening ride, came down in a first-bend incident and was ruled unfit to continue with a twisted knee.
It looked as if the Tigers’ flying start might see them through, as two 5-1s had put them into a 10-2 lead. And despite Josh Bates also coming to grief in the re-run of the third race, the home side still extended their advantage.
Berge was in stunning form and his pass of Nikolaj Busk Jakobsen in Heat 6 put Tigers 10 points up, with Ostergaard subsequently picking up maximum points from a tactical ride but the visitors being limited to a 6-3.
A series of shared races followed as Sheffield protected their advantage, Howarth overcoming Busk Jakobsen in a terrific dice in Heat 9, but two races later the Panthers began clawing back.
Fast gating from Cook and Ostergaard saw them backed by their team-mates in third place in each of Heats 11, 12 and 13, but the real blow came when Emil Grondal notched a shock win with Zdenek Holub third; Bates mired at the back.
That put the visitors ahead and although Berge was still unbeaten at that stage, Cook had found his form, and despite a brave ride by Howarth in Heat 15 to split the Panthers duo Berge could not score.
With Jason Garrity still injured, Tigers will need guest cover with Stead also ruled out for tonight’s trip to Edinburgh, although both should be back next week.
SHEFFIELD 45: Dimitri Berge 14+1, Kyle Howarth 14, Arthur Sissis 7+1, Nathan Greaves 4+1, Josh Bates 3, Simon Stead 3, Jason Garrity r/r.
PETERBOROUGH 48: Ulrich Ostergaard 15, Craig Cook 12, Emil Grondal 6+2, Nikolaj Busk Jakobsen 5, Zdenek Holub 4+1, Ashley Morris 3+1, Tom Perry 3.