It's Metallica as you've never heard them before.

The metal stalwarts were the musical guests on 'The Tonight Show with Jimmy Fallon' last night as they were promoting their new album 'Hardwired... to Self-Destruct' - but a special backstage segment saw them playing arguably their best-known song 'Enter Sandman' in a novel way.

They were joined by Fallon and house band The Roots to turn the metal standard into a cute, cuddly little singalong. Well, almost.

Watch it below: