He plays the refreshingly normal Jim Halpert on the US version of The Office.

But John Krasinski let go of his inhibitions as he channelled Katy Perry for a ‘lip sync off’ on Late Night With Jimmy Fallon.

He went head-to-head with the chat show host as they tried to give the most cringeworthy fake singing performers for the millions watching at home.

He lipped synced and he liked it: John Krasinki channeled Katy Perry during his performance on Late Night With Jimmy Fallon on Tuesday

And of course John, whose character on The Office is based on the original show’s Tim Canterbury, easily romped home as he minced around in his suit while delivering a comedic performance of the highest quality.

He gave a performance of high camp Frankie Howerd would be proud of as he writhed around the stage, at one point even whipping off his jacket.

But that was only part of the story, which began when Tonight Show host in waiting Jimmy gave a cheesily soulful performance of Melissa Manchester’s Don’t Cry Out Loud.

It only after this John, 33, was able to spring into action his unique take on Katy’s number one hit Teenage Dream.

What will Katy think? It remains to be seen whether John’s antics will have tickled her funny spot

Read my lips, no new sketches: Some of the harsher critics will be hoping this is the spot’s last outing

Easily amused: Jimmy was finding the whole affair to be an hilarious slice of late night television

Jimmy, 28, was clearly intimidated by the young pretender’s confidence, saying afterwards: ‘Fake breathing at the end and everything.’

This was just the warm up hwoeverm as Fallon then lip-synced Das EFX’s They Want EFX and Somewhere Over the Rainbow.

However Krasinski struck back himself, performing Run DMC’s Peter Piper.

Striking back: But Jimmy took the fight to the challenger as he performed They Want EFX

Not Fallon on his sword: Despite his plucky challenger’s success Jimmy was giving it everything

Over the rainbow: But he really seemed to be in his element as he performed the Judy Garland classic

However he had saved his biggest moment for last, putting everything into Boyz II Men’s I’ll Make Love to You.

He grabbed his fake earpiece, tore off his jacket, and played fashion Russian roulette by loosening his tie.

At the end, he beckoned Jimmy over to fake-sing together, as they pretended to warble, ‘I’ll make love to you, like you want me to!’

On his knees: It was scary how far John was taking his performance of Boyz II Men’s I’ll Make Love to You

Let’s call it a draw: It seemed the dynamic duo eventually decided they were evenly matched