By Erik Pedersen

SAN DIEGO, Calif. (Hollywood Reporter) - They are, with little dispute, one of rock's greatest live bands. So why did U2 choose the creaky, hot, 40-year-old San Diego Sports Arena to open their hugely anticipated world tour?

One possible reason came to mind early on and was only cemented during the rest of Monday's two-hour, 22-song show: Maybe Bono wanted a decidedly less-than-state-of-the-art sound system on opening night in case the rust, or whatever, got the better of him.

No matter the reasoning. The result was that rock's single biggest star of the past quarter-century was off his game. Sometimes way off.

While the band was typically flawless, the frontman struggled. Song after song -- new and classic -- he seemed to be holding back.

Sporting dark shades and clothes, Bono's storied swagger was intact, but he appeared satisfied to deliver theatrics over emotion. Even his ad-libs often were second-tier: "Hello, hello, we're in a place called San Diego," he sang with a straight face during "Vertigo."

Musically, however, it was another U2 triumph, led by the Edge's ringing, invigorating guitar work and anchored by the underrated rhythm section of bassist Adam Clayton and drummer Larry Mullen Jr.

The band made sure its oldest songs -- artful, moody twists on the power pop of the day -- still have teeth and that the seven new ones in the set were significant.

There were some that hadn't been heard live in years, and fact that so many radio staples were left out was simply a reminder of how many radio staples they have. Of the biggest hits, "New Year's Day" and "Beautiful Day" came across best, the latter getting a lyrical coda from the Beatles' "Blackbird."

After opening with a pair from last year's "How to Dismantle an Atomic Bomb," Bono said, "Wanna go back to where it started for us." Standing in close quarters -- as if back on a tiny stage in some dive pub -- the Irish quartet played three from their 1980 debut, "Boy."

The creeping choogle of "An Cat Dubh" gave way to a huge, Bruce Springsteen-like "hohh-ohh-ohhh" singalong. Those easy audience-participation moments recurred all night, showing how much the Boss' lovefest shows of the '80s influenced U2's live act. No wonder he and Bono inducted each other into the Rock and Roll Hall of Fame.

Typically, politics played a significant role in the show, including a midset trio of war-themed songs, a video scroll of the U.N.'s Universal Declaration of Human Rights and a moving first encore that melded Dr. King's dream with Africa's nightmare via "Pride (In the Name of Love)" and "Where the Streets Have No Name."

After "Streets," which got the night's most vigorous response, Bono discussed his ambitious One Campaign to get "1 million Americans to go to work to prove that equality exists in Africa like it exists in the United States."

It was an emphatic moment, made more so when he added, "Because we are more powerful when we act as one," and the band played its stirring "One." Still, there was a discernible lack of passion in Bono's voice and manner as he trumpeted his cause -- something Springsteen never lacks.

The stage setup borrowed its red-lit, heart-shaped catwalk from the last tour, and video was shown on a curtain of lights at the back of the stage -- a cool effect that recalled a gigantic Lite Brite. But with fewer visual distractions than in U2's pumped-up '90s tours, the focus was squarely on Bono.

His bandmates let him have the spotlight, of course, but he never appeared to challenge himself vocally, even -- no, especially -- during the usually riveting "Sunday Bloody Sunday."

Rather than pour out the emotional vocals, Bono looked almost disinterested, letting the crowd do the work on the rousing chorus. His performance -- whether reined in or simply rusty -- was a disappointment that only an event-level show could mask.

Three-quarters of a great band made this concert work for the most part, but the star can't treat opening night like a dress rehearsal.

U2 returns Wednesday night to the newly rechristened ipayOne Center at Sports Arena.

Reuters/Hollywood Reporter