Paul Simpson hailed hat-trick hero Jon Mellish after Carlisle produced one of the shocks of the season in Sky Bet League One.

Matchwinner Mellish bagged a first career hat-trick as the basement boys left Posh’s automatic promotion hopes in tatters with just their sixth win of a miserable season.

Mellish headed Simpson’s men into a 27th-minute lead, which he doubled with a smart volley three minutes into the second half.

The midfield ace completed his treble just before the hour with another spectacular volley before captain Harrison Burrows pulled a goal back for the hosts.

Substitute Jonson Clarke-Harris hit the bar late on as Darren Ferguson’s high-fliers flopped to fall 10 points behind the top two.

Simpson said: “I’m absolutely delighted for the players and the staff but even more happy for the supporters who made the long journey.

“The lads deserve huge credit for the way they went about it and they were three fantastic finishes from Jon. It’s a brilliant win and it’s all about getting some respect and pride back.

“I told Jon I wanted him to get his crazy legs going and cause problems and everyone saw that is what he did!

“We were brave to go short with our first corner and it led to Jon getting himself a free header for a good goal and the next two are fantastic finishes.

“And when we had to change to a back-five to shore things up, he slotted in at centre-back and did a good job.

“He’s an important player for us and he’s had a tough season in terms of goals as he usually gets a lot more, but a hat-trick like this is a great reward.”

Stunned Peterborough boss Darren Ferguson said: “It’s a terrible result and I’m very disappointed.

“How do I explain today? Probably the best way is that collectively we had an off-day and I include myself in that.

“Forget about league tables and how many points you have – if a team performs like we did today they will get beaten.

“We conceded three really soft goals and the lack of quality in the last third is not something I’ve seen from my players this season.

“You can get away with it when two or three players aren’t at it – but not when we all got a three out of 10.

“Maybe I gave the lads too many days off and maybe I could have made changes sooner. These are all things I have to question before I look at the level of performance.

“We’ve got a mountain to climb to get into the top two, but I’m experienced enough to know there is no reason to press the panic button.”