Macauley Bonne put the U's ahead on the half hour mark but Marcus Maddison scored twice in the next two minutes to put Posh 2-1 at the break.
The second half was a much quieter affair and the U's found it impossible to break down the home defence, despite a strong finish to the game.
Gavin Massey was denied by a handball outside the box from Alnwick and the home keeper was fortunate to receive a yellow card rather than a red.
It wasn't to be for the U's though and after five minutes of added time, the whistle went with Posh running out 2-1 winners.
In bright sunshine, both teams started the game wanting to pass quick and early but there were no scares for either keeper in the first ten minutes.
Washington for Posh and Macauley Bonne for the U’s had chances but both missed the target from crosses, Washington with a volley and Bonne with a header.
On sixteen minutes, Bonne almost got onto the end of a fantastic low cross from Brindley, following good play on the right from Gavin Massey, George Moncur and Brindley himself.
Another shot flew over the U’s bar on twenty minutes, with Anderson the culprit this time from the edge of the box.
The hosts were guilty of giving away possession and Moncur capitalised on twenty five minutes but couldn’t get enough power behind his right foot effort from eighteen yards out.
The game burst into life just before the half hour mark, with three goals in the space of three minutes.
Darren Ambrose split the home defence and Massey crossed low for Bonne to lift his shot firmly into the roof of the net to give the U’s a deserved lead.
That lead didn’t last though, as a freak Maddison cross drifted over Elliott Parish and into the far corner of the net.
It went from bad to worse for the U’s a minute later, as Maddison cut inside from the right and hit a left foot shot low to Parish’s left.
The U’s keeper got a hand to it but couldn’t keep it out and Peterborough were ahead 2-1.
From being the better team in possession, the double goal burst took the wind out of the U’s sails and the hosts were on the front foot.
They didn’t manage to test Elliott but they were certainly in the game far more than they were in the first twenty minutes.
Tony Humes had to make an enforced change a the game went into four minutes of injury time, Kane Vincent-Young coming on for the injured Matt Briggs.
A rash challenge from Gormley resulted in a yellow card for the Posh forward but it cost Briggs his chance to help the U’s back into the game.
The half time whistle went with Peterborough leading 2-1 but it was two goals out of nothing that had cost them after a good start.
The U’s went into the second half wanting to get back into the game early and were happy to push men forward as often as possible.
It only took them four minutes to get an effort away, but Bonne’s right foot effort was pulled wide after he got in on the left angle of the box.
And four minutes later, Ambrose got his curler all wrong, as he tried to find the far corner from a similar position to Bonne’s effort.
The home side were causing problems for the U’s defence but that was the risk the U’s were taking and leaving men forward was creating more chances.
Alex Gilbey got in a good position outside the box but couldn’t keep his shot down, and less than a minute later, the referee had a big decision to make.
Gavin Massey nicked the ball past keeper Ben Alnwick and the home keeper handled twenty yards out.
A free kick was given and almost everyone in the stadium thought a red card would be produced.
The referee wasn’t one of them though, and waved a yellow at Alnwick before the free kick came to nothing.
In quick succession just after the hour mark, Gilbey had a shot blocked and Ambrose hit a half volley just over the bar as the U’s continued their search for an equaliser.
Dion Sembie-Ferris and Sammie Szmodics were introduced and the former looked like he was fouled inside the box after getting past Ntlhe.
The referee again waved away appeals and the U’s were denied once more.
Gaps appeared at the back as the U’s pushed even more men forward and Maddison and Gormley both had chances to put the game to bed.
Both were wasted and it was the U’s who had the final chance of the game, Gilbey having a shot saved as the game went into injury time.
The whistle went with the hosts winning 2-1 but it was harsh on the U’s who had started extremely brightly and were hit by a goal double just after they had opened the scoring.
Things can be put right soon though, with Oldham visiting the Weston Homes Community Stadium on Tuesday evening.