The Foo Fighters rocked a Metallica classic in Kansas City, MO on October 12 with the help of a 10-year-old guitarist and video of the performance has gone viral.The band's "Concrete And Gold" tour stop at the city's Sprint Center saw frontman Dave Grohl invite Collier Cash Rule on stage at the start of the show's encore."Do you play guitar, Collier?", Grohl asked the young man, who replied "yes"; when prompted further what music he knew, Collier replied: "I know a lot of Metallica songs."The Foos leader hooked Collier up with a guitar before he launched into "Enter Sandman" while the group joined in for an abbreviated version of the 1991 Metallica hit.