Kansas City, Mo. ? After prevailing upon an arena full of fans Tuesday to sing the chorus to his 1990 ballad “Unanswered Prayers” without accompaniment – twice in a row – Garth Brooks sat back against his drummer’s kit and murmured into his signature headset microphone.

“This is so cool,” he said.

He had been relentlessly pumping up the audience during this second of nine sold-out performances at the Sprint Center, telling fans that the previous night’s crowd had been amazing, assuring them they’d know every song because “it’s all the old stuff,” bounding around the stage, distributing winks and waves.

Only two shows into his first extended round of concerts since 1998, Brooks has already reclaimed his title as the people’s pop champ, and grown restless enough to start mixing things up.

He brought out his wife (and opening act), Trisha Yearwood, for their duet, “In Another’s Eyes,” and he accompanied her on guitar as she sang her 1993 hit (with Don Henley), “Walkaway Joe.” Though the second show was shorter than the previous night’s, he closed it with a treat for enthusiasts: his excellent cover of Billy Joel’s “Shameless,” which he recorded in 1991.

Who knows what trick Brooks will pull next? That he’ll strive to surprise is as guaranteed as the rowdy sing-along to “Friends in Low Places” that happens nightly, right before he gets everybody weepy with his philosophical number “The Dance.”

His talent for being spontaneous and full of hokum in equal parts is one reason Brooks is the most commercially successful solo artist in recording history. (He was just declared such, again, by the Recording Industry Association of America , reclaiming the title from Elvis.) Only a few other artists – maybe Frank Sinatra or James Brown – have been able to command a stage so comfortably.

Brooks doesn’t often get the respect these titans do. His music is slick and embedded in a genre – country – that tastemakers tend to prefer more rough-edged. Many of Brooks’ hits were written by others, a mark down, especially for male superstars, since the rock era. And unlike many great interpreters, Brooks isn’t blessed with an exceptional voice; on Tuesday, he strained off and on, sometimes leaning toward a bellow, and momentarily losing his way when matched with his more vocally accomplished wife.

When it comes to selling a song, Brooks is a master. He knows just when to make a broad vocal gesture and when to pull back; he can make the most hackneyed phrase ring like a true confession. Melodramas such as “The Thunder Rolls” and the rodeo ghost story “The Beaches of Cheyenne” swelled to heavy-metal-worthy proportions Tuesday, tempered by romps including “Two Pina Coladas” and those soul-baring outings in which Brooks stood alone, playing guitar.

When he retired seven years ago, Brooks said his main motivation was the desire to be closer to his three daughters, the youngest of whom is now 11. In a consummately sappy flourish, Brooks announced at show’s end that his daughters, who’d been too young to see him perform before he retired, were there cheering him on. He must have been delighted to give them that gift. But he was also surely thinking that the PTA’s going to seem awfully dull now.