Bono fears U2 will split up. The singer says he and his bandmates - guitarist The Edge, drummer Larry Mullen Jr. and bassist Adam Clayton - are determined to enjoy their upcoming world tour because they fear it could be their last. He said: "We want to play for each other as much as we want to play for the crowd this time. You just don't know how long you are going to be doing this. When we walk out on stage, the hairs on people's necks go up - but what people don't know is that the hairs on our necks go up too."Larry is concerned their fans won't want to part with their money to watch them, even though tickets have been priced reasonably. He said: "Will we sell it out? Who knows? Will the economic situation have an impact? Probably. But that's not going to stop us." Larry recently admitted he wants the group to retire while they are still at the top.He said: "There will be a time when it's like, 'It's time to go.' I would like that to be on a high when you're still achieving as opposed to the curve down. That'll be sad for me. I think it'll be a more dignified time to go."