Slash sat in with Motorhead for 'Ace of Spades' in Los Angeles.
The July 4 show during Hyde Park's British Summer Time Festival will feature Black Sabbath, Soundgarden and Motorhead.
Motorhead have canceled all their shows connected with the "World's Loudest Month" series of festivals.
Motorhead takes on the Kinks in the semifinals of Ultimate Classic Rock's March Riff Madness.
Motorhead's breakthrough second album was released on March 24, 1979.
Motorhead's 'Ace of Spades' squares off against Ozzy Osbourne, Randy Rhoads and their anthem 'Crazy Train' in a very heavy round three March Riff Madness battle.