NBC is angling to keep Leno, 58, with NBC Universal but the late-night king has indicated he's ready to jump ship. Eager NBC competitors, including other networks and syndicators, are prepared to help him make the leap.

Letterman, who called O'Brien "a very funny guy," was asked about facing him as the new "Tonight" host. A cautious Letterman said he couldn't predict the outcome.

"It will be weird to see Conan at 11:30, don't you think? Which is not to say he can't succeed, but, no, I don't know what the competition will be like. I hope we're able to do OK."

In the Rolling Stone article, Letterman discusses guests including Madonna, Oprah Winfrey and Howard Stern, with the most moving remarks about musician Warren Zevon, who appeared on "Late Show" shortly before his 2003 death from cancer.

Letterman recalled his "heartbreaking" meeting with Zevon in a dressing room after the show.

"Here's a guy who had months to live and we're making small talk. And as we're talking, he's taking his guitar strap and hooking it, wrapping it around, then he puts the guitar into the case and he flips the snaps on the case and says, `Here, I want you to have this, take good care of it.' And I just started sobbing.

"He was giving me the guitar that he always used on the show. I felt like, `I can't be in this movie, I didn't get my lines.' That was very tough," Letterman said.