Grant McCann can be proud of his players' efforts and performance at Bramall Lane against an in-form Sheffield United side, but the Blades took home all three points after an early effort from Matt Done.
Done converted from close-range from a right-wing centre, but Sheffield United goalkeeper Simon Moore was by far the busier goalkeeper, making a superb stop to substitute Gwion Edwards from point blank range.
Michael Bostwick tested goalkeeper Simon Moore in the early exchanges with a curler from 20-yards after Posh had forced two successive corner kicks.
At the other end, goalkeeper Luke McGee produced a stunning save from point blank range to deny a powerful effort from Matty Done as the Blades came close to the breakthrough on nine minutes.
The home side did make it 1-0 on 13 minutes as DONE was in the right place at the right time to tuck the ball home from close-range after a low right wing centre from Freeman.
Freeman fired over on the volley after some impressive play from the Blades as we reached the midway point in the first period. Forrester saw a shot deflect wide for a corner kick on 27 minutes.
Taylor was superbly denied by Moore after wriggling into space in the penalty box and the same players were involved again moments later, this time the save was more for the cameras, but just as effective.
Maddison saw a wonderful cross elude both Nichols and Taylor in the box moments later after wonderful work down the right hand side after he was fed by Forrester.
Da Silva Lopes tested Moore with a low drive after more neat football from Grant McCann's men who were playing with confidence in possession.
Moncur linked with Maddison and found space moments before the interval, but his cut back was cleared.
The Blades made a change at the break with Stefan Scougall replacing Daniel Lafferty in a change of system for the hosts.
Duffy curled a shot wide of the target from 25-yards on 47 minutes, although keeper McGee looked comfortable it was going wide of his left hand post.
Maddison was a whisker away from levelling the scores moments later after letting fly from distance, the low drive going just wide.
Scougall was superbly denied by McGee on 54 minutes after the one-time Posh target had a go from 25-yards.
Grant McCann made a brave move on 59 minutes, making a triple substitution with Deon Moore, Gwion Edwards and Callum Chettle introduced. Sharp was cautioned for a cynical trip on Smith on 62 minutes.
On 64 minutes, Moore made a superb reflex stop to deny Edwards after a low centre from fellow substitute Moore down the right. Moore made a double stop to deny Maddison in quick succession on 70 minutes as Posh pressed.
Forrester was denied by Moore on 74 minutes after curling the ball around a defender in his way. Moncur was cautioned for a high boot on 75 minutes as the game moved into the final quarter with Posh certainly deserving something from the contest.
Bostwick lashed a shot wide from 25-yards after stepping in and beating two defenders as Posh again piled forward. Done lofted a lob wide of the target after a misplaced Binnom-Williams header.
Sheffield United: Moore, O'Connell, Basham, Sharp (sub Lavery 83min), Done, Wright, Coutts, Freeman, Ebanks-Landell, Duffy (sub Fleck 78min), Lafferty (sub Scougall 46min). Unused subs: Hussey, Ramsdale, Wilson, Chapman.
Posh: McGee, Smith, Bostwick, Baldwin, Forrester, Taylor (sub Moore 60min), Maddison, Da Silva Lopes (sub Chettle 60min), Nichols (sub Edwards 60min), Binnom-Williams, Moncur, Taylor. Unused subs: Tafazolli, Tyler, White, Oduwa.
Half-time: Sheffield United 1-0 Peterborough United
Full-time: Sheffield United 1-0 Peterborough United
Attendance: 19,555 (988 Posh fans)