Our young Blues put in a scintillating attacking performance to make it through to the next round of the Papa Johns Trophy.

We looked comfortable in the early parts of the game and Mothersille gave us the lead as he finished off a fast counter-attack after being slipped through by Josh Brooking.

Our lead was doubled in style by Casadei who smashed an effort from distance into the top corner of the net.

The Posh responded immediately though and against the run of play. From a free-kick, captain Jonson Clarke-Harris finished past Eddie Beach.

The rest of the first period saw us remain in control with Beach largely unthreatened and we scored our third of the game through Mothersille, who grabbed his brace with another exquisite finish.

Nevertheless, we gifted the Posh a way back into the match as loose passing allowed Jack Taylor, a second-half substitute to take the ball and finish easily past Beach.

Again, like most of the night, our young Blues showed calmness and restored the two-goal advantage through Ben Elliott.

A fine display with four fine goals which sees us through to the Round of 16.

The perfect start

Malik Mothersille was handed his first start for the development squad this season and looking to add to his two-goal cameo against Leyton Orient in the group stage of this competition, with our first threatening attack which was off the back of a Peterborough corner, he gave us the lead.

Josh Brooking moved through midfield and calmly found Mothersille who used his pace and strength to carry the ball towards goal and finish past Bergstrom in goal.

We consolidated our good start with a second as Casadei tore through midfield and fired from distance, finding the top corner as Peterborough's on-loan Chelsea Academy keeper Lucas Bergstrom could do nothing to stop the effort. That is the Italian’s first goal in this competition.

The Posh responded immediately to our second, halving the deficit as a chipped free-kick into the box from Burrows found an unmarked Clarke-Harris who had the simple job of side-footing into the net.

We remained on top territorially. Omari Hutchinson emphasised this with the next best effort of the game, shifting the ball onto his left quickly and firing on goal with his on-target effort being cleared away.

Remaining in control

Dion Rankine beat his man Burrows on the right and had time to deliver a cross and after a scramble in the box the ball bounced kindly into the arms of Bergstrom with the last touch coming off Zak Sturge.

We got a third goal just before half-time which solidified our first-half dominance, and it was Mothersille who got his second of the game as he notched up back-to-back braces in this competition.

The young striker peeled away to make an incisive run which was found with a sharp pass by Elliott, and he finished expertly past the goalkeeper.

We almost scored a fourth quickly after the restart as a very quick break started by Hutchinson ended with Mothersille putting in a great cross which only skimmed off the head of the stretching Casadei.

Nervy moments

The League One side were struggling to create against our young Blues as we were in total control and playing assuredly.

We were the makers of our own bad fortune as out of nothing, Taylor pressed high to win the ball in midfield, drive towards goal and slide under Beach to give his side a lifeline.

Again, despite the goal we remained in the ascendancy and Hutchinson was on the end of a flowing move, but he sliced his effort wide.

We did give away a chance to experienced striker Jack Marriott who got in behind the defence after a chipped through ball, but he blasted wide of the post.

Taylor went close again as he noticed Beach off his line and was very close drawing his side level.

Finesse at the finish

We put the game beyond our opponents' reach though as a fast break, which had caused the home side trouble all game, saw Rankine use his speed to lead the charge. He laid the ball to Elliott who showed great trickery to gain a yard of space and he struck an effort which flew past the goalkeeper.

We were creating at will at this point and Mason Burstow and Hutchinson both had good chances to get onto the scoresheet, but Bergstrom showed his class with two fine saves.

Centre-backs Brooking and Humphreys combined well as the latter put in a dangerous cross which was just missing the all-important touch to give us our fifth.

It was a fine performance capped with a development squad debut late on for Tudor Mendel-Idowu as Mark Robinson’s men put on a show against Peterborough United.

Chelsea (4-2-3-1): Eddie Beach; Bashir Humphreys (c), Josh Brooking, Alfie Gilchrist; Zak Sturge, Dion Rankine, Cesare Casadei, Ben Elliott; Leo Castledine (Tudor Mendel-Idowu 87), Omari Hutchinson, Malik Mothersille (Mason Burstow 73).

Unused subs: Ted Curd, Dylan Williams, Derrick Abu, Silko Thomas.

Scorers: Malik Mothersille 18, 45+1; Cesare Casadei 23; Ben Elliott 75.

Peterborough United (4-2-3-1): Lucas Bergstrom; Kell Watts, Josh Knight, Jonson Clarke-Harris (Jack Marriott 46), Harrison Burrows (Jeando Fuchs 72), Ricky-Jade Jones, David Ajiboye (Joe Taylor 46), Hector Kyprianou (Jack Taylor 61), Ben Thompson, Joel Randall, Benji Mensah (Nathan Thompson 60).

Unused subs: Will Blackmore, Frankie Kent.

Scorers: Jonson Clarke-Harris 26; Jack Taylor 61.

Booked: Hector Kyprianou 50; Nathan Thompson 65; Jack Taylor 72; Ricky Jade-Jones 82.