Jonson Clarke-Harris smashed in a rebound to level before the break and then struck from the penalty spot after Jimmy Dunne tripped Joe Ward.

Jack Marriott cut in and thundered a third into the top corner as Posh beat QPR for a third time this season.

Peterborough's first win in 16 league games - and first since beating QPR on 5 February in round four of the FA Cup - lifted them above Derby into 23rd place, seven points from safety.

Rangers kicked off looking to climb back into the play-off places, but a fourth defeat in their past five Championship matches - and sixth in nine - leaves them two points outside the top six in eighth place.

The hosts bossed the first half, with Ilias Chair twice fizzing efforts just wide following Amos' opener, while Andre Gray headed Albert Adomah's cross against the upright.

Posh, who had earlier struck the crossbar through Sammie Szmodics' sweetly-struck volley, were level immediately after Gray's near-miss when Clarke-Harris seized on a rebound after debutant Kieren Westwood made a superb save to keep out Marriott's close-range effort.

Rangers went close again before half-time when Chair's corner smacked the upright, but the hosts were stunned soon after the break as battling Posh hit the front with two goals in as many minutes.

QPR boss Mark Warburton made a triple change soon after, but his side could not muster a response as Grant McCann celebrated Peterborough's second away win of the season and his first victory since taking charge last month.

QPR boss Mark Warburton told BBC London 94.9:

"That was an awful second half from all of us, we've got to look at it from myself down. That was way below our level, it was unacceptable, giving the ball away cheaply.

"The boos ringing round have got to hurt, the punters pay their money and they are entitled to show their opinion. It burns in your ears.

"From a good position, to go fifth in the table with a game in hand, and a point behind third, we've thrown away three valuable points.

"All over the park, we didn't show the quality that we've shown for large swathes of the season....we need to look at ourselves and go back to basics very quickly."

Peterborough head coach Grant McCann told BBC Radio Cambridgeshire:

"I felt in the first half we started really brightly and then lost the ball in the middle of the pitch for them to break and score.

"It hurt us at the time and we did that on numerous occasions where we were guilty of losing too much possession and were lucky they didn't punish us (further).

"I'm pleased we got back into the game, good goal by Jonson, and we spoke at half-time about going for the next one and we managed to get that through a penalty.

"We carried it on with an excellent team goal from Jack Marriott so all in all a good day's work and it gives the boys confidence going into the (international) break."