Could this tour be the last for U2? Despite the fact that U2 Tickets are hard to come by - they recently sold out 90000 seats in Barcelona in 54 minutes - some in the band feel that going out on top is preferable to going out on a downward curve.

Bono stated recently that 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 noted, “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.”

Drummer Mullen is also concerned their fans won’t want to part with their money to watch them, due to current economic conditions… 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.”

Mullen 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.”