Chelsea's young stars were too slick and too quick for Peterborough United

It finished 4-2 to the Premier League side which in no way flattered them. They passed too accurately and moved too fast for a far from first-choice Posh team.

When Posh threatened a comeback with a first-half goal from Jonson Clarke-Harris and a second-half strike from substitute Jack Taylor the visitors merely raised their level to carve out scoring opportunities that were usually taken.

It’s far from the end of the world for Posh who have far more important matches to contest, but it was a performance and result that will do little for their brittle confidence. Certainly those who would be considered fringe players did little to advance their case for more League One action.

Few would have predicted the mix-and-match line-up Posh manager Grant McCann selected, apart from the shoo-in presence of on-loan Chelsea goalkeeper Lucas Bergstrom.

There was a full first-team debut for 19 year-old right-back Ben Mensah, Harrison Burrows was back at left-back, Josh Knight and Kell Watts were the chosen centre-backs, while Ben Thompson and Hector Kyprianou were an odd couple selection in centre midfield.

Joel Randall’s latest chance to prove some worth came as an advanced midfielder leaving David Ajiboye and Ricky-Jade Jones to flank top scorer Clarke-Harris.

The Posh bench was strong and numerically superior to Chelsea’s at least as the visitors named just the six possible replacements.

But that was the only superiority Posh displayed in the opening 45 minutes which the visitors completed with a 3-1 advantage, a margin that could have been much wider given the difference in class and quality.

Posh huffed and puffed, but Chelsea were slick, accurate and quick. They even managed to open the scoring in the 18th minute on the breakaway from a home corner.

Thompson didn’t cover himself in glory by dangling a weak and ineffective leg out in midfield and when the ball was moved forward to Malik Mothersille he ignored a much better option of a sideways pass to run straight at Mensah and Burrows before burying a shot into the corner of Bergstrom’s net.

The giant Finn was helpless with that shot and even more of a spectator when Italian Under 21 international Cesare Casadei smashed the ball into the top corner from 30 yards just six minutes later. Casadei was apparently purchased from Inter Milan for 15 million Euros and handed a six-year contract and one dazzling moment suggested why.

Chelsea’s adventurous attacking play wasn’t complemented by secure defensive work and Posh pulled a goal back two minutes later when Clarke-Harris was allowed to reach a chipped free kick from Burrows to score.

Watts had earlier headed a Randall corner over the crossbar and there was some Posh excitement when visiting ‘keeper Eddie Beech spilled a Mensah cross, but the danger was cleared.

Randall also inadvertantly clipped the top of the crossbar from a corner, but Chelsea always looked the most likely to score further goals.

Burrows was tormented by the skills of Dion Rankine whose quality deserved better finising from teammates.

But just when Posh looked like escaping to the interval within touching distance the under 21 side struck again. The Posh defence were pulled apart by two passes and with Watts going walkabout Mothersille was able to accept a pass, race into the penalty and fire past Bergstrom for a second time.

McCann responded by sending on Jack Marriott and Joe Taylor for Clarke-Harris and Ajiboye at the break. Marriott immediately tested Beach who spilled yet another routine save.

Jack Taylor and Nathan Thompson were sent on after an hour to try and make something happen.

And within a minute the midfielder had scored, albeit after an appalling piece of defending as goalkeeper Beach’s pass to a teammate was so slow Taylor pounced and had the simplest task of slotting past the stranded number one.

Posh were now playing wing-backs and three centre-backs with substitute Thompson at the heart of the defence, and his cute pass released Marriott, but he fired wide from a decent position.

Jones was then thwarted by a fine defensive block after reaching a Taylor pass. Posh started to hit the ball longer and Joe Taylor’s speculative effort from 35 yards with Beach stranded grazed a post.

But just as Posh started to look the stronger side Chelsea carved Posh open again with Ben Elliott this time supplying the quality finish. Within two further minutes Bergstrom stopped the scoreline becoming very messy with fine saves to deny substitute Mason Burstow and Omari Hutchinson.

Posh: Lucas Bergstrom, Harrison Burrows (sub Jeando Fuchs, 71 mins), Kell Watts, Josh Knight, Ben Mensah (sub Nathan Thompson, 61 mins), Ben Thompson, Hector Kyprianou (sub Jack Taylor, 61 mins), Joel Randall, David Ajiboye (sub Joe Taylor, 46 mins), Ricky-Jade Jones, Jonson Clarke-Harris (sub Jack Marriott 46 mins).

Unused subs: Will Blackmore, Frankie Kent.

Chelsea: Eddie Beach, Bashir Humphreys, Josh Brooking, Zak Sturge, Cesare Casadei, Ben Elliott, Dion Rankine, Omari Hutchinson, Alfie Gilchrist, Leo Castledine (sub Tudor Mendel-Idowu, 87 mins), Malik Mothersille (sub Mason Burstow, 72 mins).

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

Goals: Posh – Clarke-Harris (26 mins), Jack Taylor (61 mins).

Chelsea – Mothersille (18 mins & 45 + 1 min), Casadei (24 mins), Elliott (75 mins).

Cautions: Posh – Kyprianou (foul), N. Thompson (foul), Jack Taylor (Posh), Jones (foul).

Chelsea – None

Referee: Chris Pollard (sub Emily Heaslip, 46 mins).

Attendance: 1,523.