A Conor Sammon double and Jose Baxter’s late strike made it two league defeats in three matches for Posh as title-favourites Sheffield United won an entertaining match at the ABAX Stadium.
Sammon’s goals in either half left Posh fans feeling flat after Souleymane Coulibaly’s curled equaliser, and even better celebration, had brought the crowd to life.
Both sides created plenty of openings throughout the match, but the Blades were worthy winners having weathered Posh pressure in the second-half before Baxter sealed the points with his late goal.
Posh made two changes following Saturday’s win over Colchester with Jack Collison and Ricardo Santos starting for Jermaine Anderson and Tobi Adebayo-Rowling.
Michael Bostwick shot wide from 20 yards near the start for Posh but the warning signs were there early on that Sheffield United carried a potent threat up front as they found plenty of space in defence but could not find the final pass.
Posh were forced into an early change as Kgosi Ntlhe pulled up while Sammon attacked, and although the ball was cleared from a threatening position the full-back was forced to hobble off.
With Adebayo-Rowling and Michael Smith injured, it meant Shaun Brisley came on and went to right-back, with the classy Alex Davey moving to left-back.
But just moments after the change the new-look defence was caught out.
First Sammon saw a shot saved by the onrushing Ben Alnwick before he was set up by his strike partner Billy Sharp to fire high past the goalkeeper at his near post from about 12 yards out.
Marcus Maddison was Posh’s biggest attacking outlet and won a couple of free-kicks in dangerous positions. He also tried his luck from range a couple of times but could not find the target to follow up his double from the weekend.
The visitors continued to show their attacking threat and a one-two between their strikers - who looked much livelier than their Posh coutnerparts - nearly saw Sammon set up for a clear sight of goal, but Sharp’s pass was just overhit.
The Blades also had to make two changes, with Jamal Campbell-Ryce coming on for Stefan Scougall and Kieran Wallace coming on for Neil Collins who both appeared to have picked up injuries.
Posh then enjoyed a brighter spell, with Ricardo Santos heading over Collison’s free-kick at the back post when unmarked.
At the other end Posh’s defence was cut open once again down their left, but Sammon’s shot from the penalty spot was blocked after Kieron Freeman had squared the ball to him.
The home side then had a good chance to level the scores during six minutes of added time, but Joe Gormley shot wide from inside of the area after Maddison’s shot was deflected in his direction.
Posh had two good chances to level the scores in the second-half.
Harry Anderson was the man on the end of both moves, the first after he skinned two defenders before shooting wide from 20 yards with Gormley in acres of space and needing a simple pass to be through on goal.
Gormley was soon taken off for Coulibaly before Anderson got on the end of Maddison’s excellent cross from the left but his volley was saved by Mark Howard.
The Blades continued to ask questions of the Posh defence, in particular through Campbell-Ryce, but five minutes after coming on Coulibaly brought the crowd to life as he cut in from the left and curled a brilliant strike past Howard into the far corner before running half the length of the pitch and bringing out a back-flip as he celebrated his first competitive goal for the club.
The atmosphere cranked up several levels but the Blades held firm and hit back.
Sharp fired wide twice, the second time when well placed, before Gabriel Zakuani had to throw his body in the way as the ball was twice fired towards the Posh goal.
However, the reprieve was short-lived as Che Adams again found space down the left and passed it to Sammon who put it low into the corner from inside the area.
Posh manager Dave Robertson responded by bringing on Jack Payne for his first appearance of the season in place of Davey.
But it was the visitors who struck again as Baxter exchanged passes with substitute James Wallace before firing in off the underside of the bar from just inside the area to give the visitors a deserved third goal and a deserved three points, despite a couple of late Coulibaly efforts which flew over.
Posh: Ben Alnwick, Alex Davey (sub Jack Payne, 73 mins), Ricardo Santos, Gabriel Zakuani, Kgosi Ntlhe (sub Shaun Brisley, 14 mins), Harry Anderson, Michael Bostwick, Jack Collison, Marcus Maddison, Joe Gormley (sub Souleymane Coulibaly, 54 mins), Conor Washington.
Subs not used: Dion-Curtis Henry, Jon Taylor, Kyle Vassell, Jermaine Anderson.
Sheffield United: Mark Howard, Kieron Freeman, Neil Collins (sub Kieran Wallace, 25 mins), Jay McEvely, David Edgar, Stefan Scougall (sub Jamal Campbell-Ryce, 19 mins), Chris Basham, Jose Baxter, Che Adams, Billy Sharp (sub James Wallace, 75 mins), Conor Sammon.
Subs not used: George Long, Marc McNulty, Martyn Woolford, Louis Reed.
Goals: Posh - Coulibaly (59) Sheffield United - Sammon (15, 72), Baxter (85)
Bookings: Posh - Anderson (foul), Santos (foul), Zakuani (foul), Collison (foul), Brisley (foul.
Blades - Sammon (goal celebration), K Wallace (foul)
Attendance: 6,526, (1,578 Sheffield United)
Referee: Nigel Miller 6