Peterborough United can start planning for the play-offs after this chaotic defeat at the hands of Carlisle United

Just where this performance came from is anyone’s guess, from both sides. Posh had so much to play for and this was a supposed banker against a team who had lost 12 of their previous 14 games. Football remains a funny old game.

Take nothing away from Carlisle. This result won’t save them from the drop, but the the leakiest defence in the division defended in some comfort against League One’s most prolific attack and they showed Posh how to shoot straight, well John Mellish did with two second-half volleys to follow a first-half header to complete a terrific hat-trick. He’d only scored two goals all season before this game.

Posh replied quite quickly after falling 3-0 down early in the second-half when Harrison Burrows claimed his 10th goal of the season, although a flick from Joel Randall may have been the decisive touch. Substitute Jonson-Clarke-Harris then missed a sitter with his head with 25 minutes to go when a second goal might have prompted panic in a team not used to winning.

Clarke-Harris also hit the bar from close range late on, but by then Posh had become chaotic rather than cohesive. Indeed Carlisle looked as likely to score as Posh did in the final stages.

The Posh team that started the defeat at home to leaders Portsmouth was given a vote of confidence to tackle the side at the bottom. Malik Mothersille was given the nod at centre forward again ahead of Ricky-Jade Jones and Ryan De Havilland again deputised for Hector Kyprianou in central midfield.

You wouldn’t known there was 47 points between the sides at the start of play from the first 45 minutes though. Posh enjoyed almost unlimited possession, but created nothing, nada, not a thing until Kwame Poku shot over the bar in added time after chesting down an Ephron Mason-Clark cross.

Otherwise some of the sloppiest passes seen all season ensured visiting goalkeeper Harry Lewis had nothing to do apart from walk slowly around his penalty area taking goal-kicks.

Posh actually started okay, knocking the ball about at a decent tempo, without creating anything, but they fell behind to a sucker punch on 27 minutes as Carlisle made a rare venture forwards.

They won a corner which was taken short and Jordan Gibson, an early substitute, delivered a cross that Mellish attacked as Posh defenders watched to power home a close range header.

Mason-Clark curled over within 60 seconds, but it was a rare moment of promise in front of an increasingly frustrated crowd.

It got worse before it got better after the break. Mellish volleyed home on 48 minutes after pouncing on a weak defensive header and he repeated the trick on 59 minutes as Posh again failed to get any defensive pressure on the ball.

Manager Darren Ferguson made three substitutions after the second goal and the formation changed regularly. Josh Knight should have reduced the arrears to one goal after Jones played him through, but inexplicably passed, badly, when he should have shot. Usually it was the other way around with players shooting from 25 yards when passes to better-placed teammates were on.

Posh did pull a goal back within four minutes of falling 3-0 down when Burrows drilled home from the edge of the box with the aid of a Randall flick. Clarke-Harris then headed wide from close range and Mason-Clark’s low shot was kicked away by Lewis. It was the only save of note Lewis was forced to make.

A Clarke-Harris flick against the bar and a Jones miskick when well placed eight yards out were the last moments of excitement for the home crowd as Posh replaced their normal poise in favour of desperate crosses and shots

It was all quite alarming given the rewards still available. Maybe Wembley was on their minds.

Posh: Jed Steer, Harrison Burrows, Ronnie Edwards, Josh Knight, Jadel Katongo (sub Ajiboye, 52 mins), Ryan De Haviland (sub Jonson Clarke-Harris, 52 mins), Archie Collins, Ephron Mason-Clark, Joel Randall (sub Emmanuel Fernandez, 72 mins), Kwame Poku (sub Michael Olakigbe, 79 mins), Malik Mothersille (sub Ricky-Jade Jones, 52 mins).

Unused subs: Nicholas Bilokpaic, Romoney Crichlow.

Carlisle: Harry Lewis, Jack Armer, Sam Lavelle, Dan Butterworth (sub Alfie McCalmont, 65 mins), Taylor Charters (sub Jordan Gibson, 23 mins), Jack Ellis (sub Josh Emmannuel, 77 mins), Dylan McGeouch (sub Georgie Kelly, 77 mins), Jon Mellish, Ben Barclay, Harrison Fall, Luke Armstrong.

Unused subs: Gabe Breeze, Jack Diamond, Sean Grehan.

GOALS: Posh – Burrows (63 mins).

Carlisle – Mellish (27 mins, 48 mins & 59 mins).

CAUTIONS: Carlisle – Ellis (foul), Mellish (foul).

REFEREE: Will Finnie 5.

ATTENDANCE: 10,080 (480 Carlisle).