Despite the stacks of guitar amplifiers onstage, Keith Urban's music became more powerful during the quieter moments of his Thursday night (March 17) concert at the Ryman Auditorium in downtown Nashville.

It was just one year ago when Urban sold out his first headlining show at the world's most hallowed venue for country music. This time around, he and tourmate Katrina Elam are doing a three-night stand that continues through Saturday (March 19). As an indication of Urban's growing popularity, he sold out all three shows at the auditorium that seats a little more than 2,300 people.

With many of his adoring female fans holding homemade signs, Urban looked up into the balcony to jokingly thank those who made the short drive from the Middle Tennessee suburbs of Smyrna, Franklin and Bell Buckle. After learning that two young women flew 450 miles to attend the concert, he asked where they came from.

"Chicago?" he said. "I think we're playing there soon, I hate to tell you."

The two fans from the Windy City will be telling their friends the trip was well worth the trouble, especially after Urban invited them onstage for a quick chat and a hug. On top of that, they -- and the entire audience -- got another huge surprise when Urban introduced Kenny Chesney as the evening's special guest.

With the exception of Chesney's involvement, Urban's concert was essentially a slightly expanded version of the shows he's been delivering on the road for the past five months. Opening with a brief acoustic snippet from the song, "These Are the Days," Urban quickly hit the electrical switch as he strutted around the stage performing "Days Go By." He maintained the voltage through favorites such as "Raining on Sunday,"

"Where the Blacktop Ends" and, from his album with the Ranch, "Walkin' the Country."

Moving back to the acoustic guitar, Urban was obviously having fun when he performed the redneck-themed "Homespun Love." Offering an array of guitar riffs, Urban carefully moved the instrument in front of the monitor speakers for some experiments in controlled feedback before make a segue into Smiley Lewis' "I Hear You Knockin'" and finally ending the song.

The power of Urban's performance was heightened with his acoustic version of his first No. 1 single, "But for the Grace of God." Stripped from the more intricate instrumentation, it was easier to become immersed in the subtleties of Urban's voice. He's a fiercely talented guitar player, but he also possesses one of the most recognizable voices in contemporary country music. That's no small accomplishment.

Bassist Jerry Flowers, another member of the Ranch, recently returned to Urban's band. During the acoustic set, they celebrated the reunion with "Desiree," a song from the Ranch's album. It was a stunning performance and a reminder that Flowers has a remarkable voice, too.

Before the acoustic segment was completed, Urban invited Chesney onstage to help him sing Merle Haggard's "Mama Tried." Chesney's comical gestures and facial expressions forced Urban to laugh his way through much of the song. It wasn't a performance that either of them will point to as an artistic peak, but that wasn't the point. It was one of those terrific "Nashville moments" where friends support friends while extending the town's reputation of Music City.

Urban's entire five-piece band returned to the stage to gradually ease back into an electric sound during the concert's homestretch that began with his latest single, "Making Memories of Us," written by Rodney Crowell. Moving through the musical wardrobe with songs such as "Jeans On" and "You Look Good in My Shirt," a night filled with singalongs hit its audience participation pinnacle with his version of Tom Petty's "Free Fallin'."

Closing the regular part of the concert with "Somebody Like You," Urban and his band returned for the usual encore of "Tonight I Want to Cry," "Who Wouldn't Wanna Be Me" and "These Are the Days."

Elam's set consisted primarily of songs from her self-titled debut album released in October. At the age of 21, Elam is surprisingly assured and authoritative as she works the stage and the crowd. With some memorable songs such as her debut single, "Unbreakable," the Oklahoma native and her band deserved better than the high-decibel audio mix that often overtook her vocals during her debut on the Ryman stage.