Sonisphere festival has stepped up its game for the 2011 line up with the new additions of two heavyweight rock bands.

Metallica and Slayer have been officially confirmed to perform at the Knebworth festival in July next year.

Friday, July 8 will see not only the ‘Master of Puppets’ and ‘Angel of Death’ rockers on the stage, but joining them will be Megadeth and Anthrax.

Tickets are available now and the event will take place between July 8 – 10, 2011. 

Watch Metallica perform 'One' at the 1997 Reading Festival here: