Writer-director Cameron Crowe's documentary The Union , about the re union of Elton John with his onetime idol Leon Russell, has been selected to open Robert De Niro's Tribeca Film Festival on April 20. In an unconventional launch, the festival plans to screen the film outdoors at the North Cove at the World Financial Plaza. The screening will be followed by a live performance by John. The Union is the first documentary directed by Crowe ( Say Anything, Almost Famous, Jerry Maguire ) and brings him closer to his early career as a teenage journalist for Rolling Stone , when he interviewed some of the top recording stars of the early 1970s. "As a longtime fan of both artists, it was a pleasure to spend a year filming their collaboration," Crowe said in a statement. "We can't wait to show it to one of the greatest audiences in the world, the Tribeca Film Festival."