Carrie Underwood has just started her set here at Gwinnett Arena, co-headlining with Keith Urban.

Dressed in a demurely sexy black getup with four-inch heel leather boots, Carrie started right on time at 7:30 p.m. with a rabble rouser from her second album “Flat on the Floor.” Barely half the crowd was at their seats but the numbers increased rapidly in the intervening minutes.

She took advantage of a runway that ran more than halfway across the arena, singing “Just a Dream” from about 15 rows in.

Personality-wise, Carrie is no Kellie PIckler. She’s more poised than she was three years ago after plenty of practice on stage, but her patter sounded stagey and scripted, at least in the early going. Her bag of stage tricks are fairly limited to wiggling her legs and waving to individuals in the crowd.

But vocally, she sounds amazing, as usual. And it seems so effortless. If she missed a note, she hid it well. The purity of her voice permeates every corner of the arena. She can hold high notes for hours if need be, as it seemed during “I Know You Won’t.”

Despite her rather vanilla persona, “Before He Cheats” proves she can play tough and get away with it. And on her latest single, “Last Name,” that bit of Carrie sass comes out in full force. Heck, she can somehow get away with doing Guns n’ Roses’ “Paradise City” without a trace of irony or self deprecation.

Two thirds through, she got serious. “I want to thank you guys for putting me on this stage,” she said. “I don’t know why but I’m about to cry… I get to watch ‘American Idol.’ It’s so amazing to think that a few years ago, I was on that stage. You guys helped me through. I can’t believe there are five people left. It’s incredible I managed to survive the next two years that followed. It’s been an amazing, amazing ride. Thank you guys. God bless you for it.”

Then during “Don’t Forget To Remember Me,” she literally stopped partway in tears and could barely finish the song.

When she sings “All American Girl,” that is a title she fits perfectly.

The set list so far:

Flat on the Floor

Wasted

Get Out of This Town

The More Boys I Meet

Just a Dream

Jesus Take the Wheel

I Know You Won’t

I Ain’t in Checotah Anymore

Last Name

Don’t Forget To Remember Me

TWisted

All-American Girl

So Small

She performs again Friday night at G\winnett Arena. Though sold out, on Thursday, they opened up a few extra seats that may still be available at Ticketmaster.