(AP file photo)

CALGARY -- For about 200 Avril Lavigne fans, it was the best damn thing that could've happened.

The pop-punk princess performed a private concert Thursday afternoon in downtown Calgary at the Grand Theatre, unveiling material from her much-awaited forthcoming third album.

And then, like a blustery chinook in February, she blew out of town as suddenly as she had arrived.

The one-time-only event, which had been announced this week on the singer's website and was primarily for members of her fan club, was taped for a CBC special tentatively set to air April 2.

That's about the time Lavigne will be unleashing a fresh wave of publicity to tout The Best Damn Thing, her follow-up to 2001's Let Go and 2004's Under My Skin.

Calgarian Kerianne Sproule was one of those who attended the show, which kicked off at 1:45 p.m. and lasted for about an hour.

"She sounded a lot more punk," Sproule says of the trio of new songs Lavigne previewed, including I Wear the Pants.

(Speaking of which, Lavigne's newly minted husband, Deryck Whibley of Sum 41, didn't accompany his bride into town, according to Sun sources.)

"(The new songs) were really catchy. She sounded more mature."

Another source told the Sun Avril watchers shouldn't expect much of a departure from her patented four-chord pop sound. Nor, apparently, should they expect a glammed-up Lavigne, a la Christina Aguilera.

Sproule says the still-blond Lavigne, who wore her engagement and wedding rings, performed in Converse runners, blue jeans and a shirt "with a weird, abstract design of a dog" on it. "She seemed relaxed and easygoing ... She didn't really talk too much."

After an hour, Lavigne told the crowd she was losing her voice and declined doing an encore. By late afternoon, she was on a charter flight out of the city.

The Best Damn Thing is due out April 17 with the first single, Girlfriend, expected on ITunes later this month.