Owura Edwards, Harry Leonard and Ethan Williams saw Posh establish an unassailable first-half lead and although City did breach the away side’s backline through Emil Riis’ finish, it proved to be a mere consolation for the Foxes.
Sitting 17th in the current standings, Doncaster Rovers are next up on Filbert Way in another 3pm BST kick-off on Saturday 17 October.
Missed opportunities
Backed by a big King Power Stadium crowd, it was a frantic opening with both sides clearly eager to get back to league duties after an extended break.
City have struggled to gather momentum, while Peterborough’s start to the season led to a change in the dugout and the visitors looked keen to turn that around under their new manager, former Fox Robbie Savage.
An early Leicester chance saw Riis chase down Caleb Okoli’s ball forward, latching on to it and firing a shot across the face of goal. Landing wide, it was an early indication of the attacking nature of the game.
Alex McCarthy had to make a smart stop at the other end moments later, however, tipping Leonard’s header onto the crossbar. John Lundstram, captain on his home debut, then took on Louis Page’s pass when Bobby De Cordova-Reid looked to be in a better position to strike, and although the Jamaican did manage to get a shot away in the end, it was rushed and sent over the top.
First half damage
Peterborough were quickly back on the attack and made us pay. Edwards, from the left, cut inside Olabade Aluko and was lethal with his finish, finding the opposite corner to beat McCarthy.
Eyeing a response, Will Alves’ cross made its way to Liam Cullen, who did well to get the ball under control but struggled to find room for a shot, which caused a brief moment of pinball in the Peterborough penalty area.
More success came for Alves down the left, cutting inside but unable to test Alex Bass with a curling effort. Riis, on the other hand, did force a save from his powerful strike, as Leicester continued the hunt for an equaliser.
The second would come with 10 minutes to go until half-time. Bolu Shofowoke showed a turn of pace to get into space with Leonard arriving to finish from close range.
It went from bad to worse for the Foxes when Ethan Williams drove into the box and took aim; his shot deflecting off Warren O’Hora and wrong-footing McCarthy, who could do nothing to prevent a third.
One back, but not enough
Three half-time substitutions saw Wes Burns, Kamari Doyle and Ilari Kangasniemi enter the fray, the latter, on his home debut, mustering our first attempt of the second period - a blocked shot when up for a corner.
As we pushed more bodies forward, the gaps inevitably opened up, with Liam Kelly almost taking advantage, slamming wide from a first-time hit.
But that attacking impetus did pay off when two substitutes combined. Doyle charged forward, finding Burns, who picked out Riis in the middle, sliding in to net his fourth goal in Leicester colours and second in as many games.
McCarthy had to be alert to stop Matthew Garbett from instantly quashing hopes of a comeback, before Doyle fired straight at the ‘keeper after Alves’ cross was initially kept alive by substitute Sammy Braybrooke.
On from the bench, Danny Ormerod twice diverted wide in a late foray forward for Posh, who might have added to their clear advantage, but by then the points were already heading back to Cambridgeshire.