Darren Ferguson' s side matched their opponents on the possession front, but were unable to cope with a masterclass from opposition forward Fred Onyedinma, who set up two goals and scored one in a dazzling debut performance.
Speaking after the game, Posh boss Darren Ferguson said: “They started the game strongly, but we saw that through and got a bit of control in the game. We just needed to play with a little bit more belief.
“The reason we lost the game today was poor decision-making and a lack of concentration. We made it difficult for ourselves. You can’t give goals like that away in the second half.
“It’s nothing to do with the level, but the decisions we made. Even the first goal. We’ve got to stop the cross. It’s a foul though, he’s got both hands on my centre half, but sometimes you get and the sometimes you don’t.
“For the second, Frankie Kent made a terrible mistake and we were punished and three minutes later they put a cross in the box and the boy’s got no-one near him, the wing back hasn’t dealt with it and it’s an easy two goals.
“Then at that point you’re thinking this could be four or five, but it was never that sort of game.”
Next up, the Posh will look to bounce back tomorrow evening, when they take on Plymouth Argyle at London Road.
We’ve gathered the best of today’s transfer speculation below…

5. Coulson set for Boro exit
Middlesbrough boss Neil Warnock has revealed defender Hayden Coulson is set to leave the club, and that a replacement is currently being actively sought. Coulson has been with his boyhood club since joining the youth academy in 2012. (Football League World) Photo: George Wood

6. Blues keen on Taylor
Birmingham City look set to step up their efforts to sign Nottingham Forest striker Lyle Taylor, with Sam Cosgrove looking likely to leave the club. Preston North End have also been linked with the ex-Charlton Athletic star. (Birmingham Mail) Photo: Alex Burstow

7. Blades ready double raid
Sheffield United have been tipped to swoop for both QPR's £6m-rated goalkeeper Seny Dieng and Crewe winger Charlie Kirk. The Blades are yet to sign on loan a single player this summer, despite the season starting last weekend. (The Sun) Photo: Jacques Feeney

8. Barca favourites to sign ex-Swan
Barcelona have been named favourites to sign ex-Swansea City midfielder Renato Sanches, who played on loan for the Welsh side back in 2017. He's now reignited his career with Ligue 1 outfit OGC Lille, and was part of Portugal's Euro 2020 squad. (SkyBet) Photo: DARKO BANDIC

