The 49-year-old director refused to reveal the identity of the musician tapped for the 24th James Bond film, reported Entertainment Weekly.
"When will you find out? You'll have to ask Barbara Broccoli, but I would say - on the basis of the last one - very, very late in the day," he said.
'Spectre' will see Daniel Craig return to the role of Bond alongside a cast including Lea Seydoux, Monica Bellucci, David Bautista, Andrew Scott, Ralph Fiennes, Naomie Harris, Ben Whishaw, Rory Kinnear and Christoph Waltz.
'Spectre' will be released on November 6, 2015 in cinemas around the world.