Irish rockers U2 kick off their Vertigo world tour tonight at the San Diego Sports Arena. And after the success of their Elevation trek, the Dublin band -- who will play four sold-out shows at the Air Canada Centre in September -- has a lot to live up to.

Not that long-time band manager Paul McGuinness sounds at all worried about the group, whose longevity after 27 years seems assured given their most recent album, How To Dismantle An Atomic Bomb, has sold nine million copies worldwide largely on the success of just one single, Vertigo.

The song also netted U2 three Grammys in February and, earlier this month, they were inducted into the Rock And Roll Hall Of Fame.

"They're very good, I think that's probably the key," McGuinness told the Sun in a Canadian newspaper exclusive last week from Vancouver.

"And they're very ambitious and they work very hard and they really enjoy it and they're very proud of what they do. And, in a way, there's a boxing analogy really. They are the champions. And if somebody else wants to be the champion they have to take the title away. But U2 are going to hold on to it. They're doing their best work creatively, I think, now. If they ever kind of burned out musically, that would probably be when the band ended -- but there's no sign of that."

U2, who built their Vertigo stage at Vancouver's GM Place in late February, arrived in the Canadian West Coast city to rehearse immediately after their Rock And Roll Hall Of Fame induction on March 14 at a ceremony in New York City.

After about a week in Vancouver -- U2 actually started music rehearsals in both Europe and Mexico a few months ago -- the band headed down to Los Angeles for dress rehearsals this past Thursday until Saturday at the L.A. Sports Arena.

McGuinness didn't want to give away much about the Vertigo production but did say like Elevation, it will have a 360-degrees view with the stage at one end of the venue and general admission -- no seats, just standing -- on the floor.

"What used to happen in arena situations in (North) America was that the front few rows, the tickets would inevitably end up on the black market and in the hands of wealthy middle-aged people and if you're performer, that's not who you want to see past the mic line. So this (general admission on the floor approach) has been, in a way, very effective in getting the fans as close to the stage as possible because it is from music fans that comes the energy that produces the performance."

McGuinness is anticipating a "very emotional and very energetic" night of music that's "visually astounding."

"There will be no one else on stage apart from those four guys," he says referring to U2 singer Bono, guitarist The Edge, bassist Adam Clatyon and drummer Larry Mullen Jr. "It's still that same kind of crisp image of four familiar people whose names you know making an enormous noise. That's what always kind of excited me and I think then about the bands we admired when we were kids. I still find it very exciting."

As for Toronto's quick four sell-outs on Sept. 12 and 14, 16, 17 at the ACC -- tickets vanished in all of 45 minutes -- McGuinness wasn't that surprised given the band's long history with the city.

"We played the El Mocambo in 1980," says McGuinness. "And funnily enough we were playing for (Toronto's) Michael Cohl. He was the promoter. So we actually go back quite a long way. We got played on Canadian radio more at the beginning than in America."

Toronto will also be the starting point for the second leg of U2's North American tour, after playing Europe in the summer. After a month-long break once their European tour wraps up in mid-August, McGuinness said U2 might require a day of rehearsals in Toronto before the first show on Sept. 12.

But, in the meantime, he was pleased to hear the Toronto International Film Festival, running Sept. 8-18, would be in full swing while the group was in town. "If the film festival is on, that's a bit of a temptation," says McGuinness. "(U2) have a lot of friends that make films like Neil Jordan and Jim Sheridan, and Bono wrote a film himself a few years ago and I'm one of the owners of the film studios in Ireland, and I used to be an A.D. (assistant director). So the Toronto Film Festival, that looks like a great opportunity."