Kenny Chesney

SPIRIT IS WILLING: Chesney lasted about 90 minutes before pals such as Kid Rock and Uncle Kracker helped out. (Allen J. Schaben / Los Angeles Times)

There's cause to celebrate any time a musical juggernaut as meticulously planned and well-oiled as one of today's arena pop concert tours deviates from the script.

Even when, as was the case at Kenny Chesney's show Wednesday at Staples Center, the outcome isn't inspired musical spontaneity, but more like closing time at the karaoke bar.

One reason this 40-year-old from Luttrell, Tenn., keeps taking home entertainer of the year awards from the major country music trophy-giving bodies is that it's so abundantly clear how much of himself he invests in every performance. So when it appeared he had blown out his voice around the 90-minute mark during his first show in three years in L.A. proper, he trotted out some celebrity vocal power to help him make it through the rest of the night.

That happened to be rap-rocker Uncle Kracker, who had successfully collaborated with him on his 2004 single "When the Sun Goes Down," and who took the lead on a handful of songs as the show drew to its sputtering conclusion. Then, to the screaming delight of the near-capacity crowd, Chesney coaxed Cracker's boss, Kid Rock, from the wings onto the stage for some hand-waving neo-country/rock/hip-hop cheerleading.

They stumbled through good-natured stabs at Steve Goodman's country-cliché sendup "You Never Even Call Me by My Name" (as popularized by David Allan Coe) and dusted off the Allman Brothers' Southern-rock mainstay "Midnight Rider." All the while Chesney attempted to rest and water his overtaxed vocal cords, which still sounded fairly worse for wear when he took the reins back on "How Forever Feels."

Recently Chesney refused to derail a show despite breaking his foot in the middle of a performance. Audiences, country fans especially, love a trouper, and visible effort is typically handsomely rewarded on the concert trail. And so Chesney, year in and year out, sells more tickets than any other country act, and frequently more than any other touring musician, period.

He's more energetic than George Strait, cuddlier than Toby Keith, is less schizophrenic than Brooks & Dunn and rocks harder than Brad Paisley. His closest competitor is Keith Urban, another relentlessly pleasant, magazine-cover handsome country singer and songwriter whose songs rarely plumb emotional depths, but still allow listeners to feel good about him and themselves.

Indeed, shortly into Chesney's show he told the crowd, "I know everybody's got troubles, but we're going to forget them for the next 90 minutes!"

Chesney largely kept his promise, sticking to his upbeat, Jimmy Buffett-esque party- always themes and tuneful celebrations of tropical locales where the biggest dilemma is choosing beer or margaritas.

Even when he turned comparatively introspective midway through the show -- and he deserves credit for stringing together several ballads rather than merely sprinkling them throughout for tempo variation -- he kept fans at arm's length.

"Better as a Memory," from the current "Just Who I Am: Poets & Pirates" album, could easily serve as a bittersweet epitaph to his brief marriage to Renée Zellweger. But there was no mention of any real-life specifics that would bring a sense of personal connection to such material, and he further distanced himself by prefacing it with a generalized remark that it was a love letter "I've had to write several times in my life."

For someone who also advises that his fans "Don't Blink" lest they miss all the richness that this all-too-short life has to offer, Chesney might try heeding his own hit's words.

LeAnn Rimes preceded him with a short set heavy on vocal power and Americana rock-leaning arrangements, demonstrating how far she's moved away from the Patsy Cline-like country of "Blue" that launched her career as a teenager.

When she offered up a snippet of that song, it was no longer the steel-guitar driven traditional country tune it started out as but a cabaret-lounge version with moody piano backing.

And the wonderful lunacy she's shown at times by covering such non-country material as Prince's "Purple Rain" was nowhere in sight -- replaced by undistinguished pop-rock.

randy.lewis@latimes.com