Sir Elton will begin a European tour in September
Sir Elton John has teamed up with US rockers Alice in Chains for a tribute song to the band's late singer.
The star plays the piano on Black Gives Way to Blue which was written for frontman Layne Staley who died from a drug overdose in 2002.
Singer and guitarist Jerry Cantrell said the track was a "real, raw openhearted song for Layne".
The song is the title track from the band's first studio album in 14 years and will be released next month.
"We were thinking about adding piano to the track and a friend suggested we call Elton," Cantrell said.
"I decided it was worth trying and wrote Elton an email explaining what that song means to us.
"We sent him the track and got a call shortly after saying he thought it was beautiful and that he wanted to play on it."
Sir Elton said: "I've long been an admirer of Jerry Cantrell and when he asked me to play on Black Gives Way To Blue, I was very flattered and couldn't resist."
Staley was found dead in his apartment in April 2002 at the age of 34.
A coroner concluded the singer died accidentally of "acute intoxication" from the combined effects of using heroin and cocaine.