Bono says a part of him is "now a void" following David Bowie's death.
The U2 frontman has penned a heartfelt tribute to the late singer, who passed away earlier this month aged 69, in which he reveals the 'Starman' hitmaker's music changed his life when he first heard it as a teenager, and insists the musician was a real "rock star".
He wrote: "Bowie's musical landscape affected you in a way that is completely different from all the other music around it. You have to close your eyes, imagine you don't speak English and just feel the songs and say, 'What part of me is being played by those notes?' Or 'Who else plays them?'
"And in his case, the answer is nobody. That part of me is only played by David Bowie. So that part of me is now a void - I have to find other ways to wake it up. But it woke me up when I was 14.
"I've played at being a rock & roll star, but I'm really not one. David Bowie is my idea of a rock star. Right now, I'm in Myanmar, a little cut off from the reaction to David's passing, but I can assure you the sky is a lot darker here without the Starman."
Bono says he was "more of a fan" than a friend of David's but admits the pair did used to have "playful" banter which would sometimes be taken too far.
In a piece about David for Rolling Stone's Bowie memorial issue, Bono wrote: "I'd like to consider myself David's friend, but I'm more of a fan.
"He came and visited us when we were mixing 'Achtung Baby' - and, of course, he had introduced us to Berlin and to Hansa Studios. We had a playful sort of banter - he would really go there in conversations, and we would even occasionally hurt each other's feelings."