Even your idols have idols. Rock legend Elton John has always admired singer-songwriter Leon Russell.
"He was my biggest influence as a piano player, a singer and a song writer," John said.
After more than 250 million albums sold worldwide, John returns to his musical inspiration.
"It's this time of my life. It was so great to go back ... and make a record with someone I wanted to be like," John said of Russell, "even though I don't have the range of piano technique or the voice."
Their partnership came about in 2009, when John was on safari and listening to a Leon Russell album. The music brought him to tears.
"I'm in Africa listening to his greatest hits, and I get overwhelmed with emotion. Takes me back to the -- one of the happiest times of my life when I'm breaking America. He was my idol in the late '60s, early '70s. And I just got very emotional ... and it was 'Back to the Island,' a song called, 'Back to the Island.' I was sobbing."
The music inspired John to track down Russell, whom he hadn't spoken to in nearly four decades.
"So I called Leon and I said, 'Leon, hello, it's me. I haven't spoken to you in 38 years. But I just wanted to tell you this story.' I said, 'Can we ... do you want to do an album?' He said, 'Well, hell, yeah. Let's do an album.'"
Russell never stopped recording, but he had fallen from the spotlight. In the 1970s, when John was just a young up and comer, Russell had already worked with almost every major musician, including music legends such as B.B. King, Barbara Streisand, Ike and Tina Turner, the Beatles, Frank Sinatra.
But their collaboration almost didn't happen. Right before the two men went into the studio, Russell experienced a spinal fluid leak and had to have brain surgery.
"It's all fine," Russell said. "I was a little bit groggy there for a week or two, but it's all right."
"It was amazing that after such a major operation, 5½ hours ... and then he would come into the studio two or three hours a day -- and you know, play and sing and then go home and rest," John said. "And you saw him get stronger every day he came in. Music does that to people. You know, it rehabilitates them."
Russell joked that by the time he arrived at the studio on the first day, John had already written five songs. "I didn't have much to do," Russell said.
Recorded live in the studio, "The Union" was produced by T Bone Burnett and includes a variety of musical genres from R&B, soul, gospel, country, pop and rock. Icons Neil Young and Brian Wilson provide guest vocals on the 14-track record, along with legendary R&B organist Booker T. Jones, steel guitarist Robert Randolph and a 10-piece gospel choir.
While John is passionate about his latest work, he is equally passionate about the work of his foundation. Monday night, the duo played at an annual benefit for the Elton John AIDS Foundation, which supports HIV prevention programs in an effort to get rid of stigma associated with HIV/AIDS.