We already know that Lady Gaga is pretty much finished with the follow-up to her smash full-length debut, The Fame. But now we finally have a peek at some of the material that might be on the album, thanks to footage of Gaga performing at Elton John's White Tie and Tiara Ball last Thursday.

"This is a brand-new record that no one's ever heard before ... ever," she said while seated at one of her signature deconstructed pianos and wearing a bedazzled black bra and panties with black boots. "And I've never, ever played it live, ever."

On her Twitter, she described "You and I" as a "new song ... written in NY on the piano I grew up on."

Sounding a tad hoarse, Gaga described the song to her audience as a bit of a "rock-and-roll tune," predicting that for that reason it will not likely get used as a single, but that it is "very dear" to her heart.

"It's been a long time since I came around/ It's been a long time, but I'm back in town/ And this time, I'm not leaving without you," she sang, describing a whiskey-breathed lover for whom she's pining.

"He said, 'Sit back down where you belong, in the corner of my bar with your high heels on,' " she continued, her voice rising and getting a bit more growly just before the band came in and provided a swaying backdrop to the bluesy rocker. " 'Sit back down on the couch where we made out the first time, and you said to me/ "Something, something about this place/ Something about lonely lights and my lipstick on your face." ' "

She wasn't kidding about the song having a rock edge, as the tune eschewed most of her dance flavor, right down to a rollicking barrelhouse piano solo, during which she stood up on the piano bench and bashed out some John-worthy runs on the black and whites. She finished the tune crouched on the bench, wailing, "You and I," while pumping her fist, before giving it a big finish that included kicking a heel up on the keyboard and lying across the piano bench with her head on the ground.

Gaga tweeted about her performance at the 12th annual fundraiser for the Elton John AIDS Foundation, writing, "What a brilliant evening with wonderful friends. Thank you to everyone who donated to the Elton John AIDS Foundation. What a magical stage."

Gaga also took the stage in a wheelchair with her chest covered in fake blood and accompanied by an oiled-up male dancer for a run through "Alejandro," and she performed her ballad "Speechless." During the latter, John came out and joined her for a dueling-pianos showdown, trading off verses on the tune dedicated to Gaga's dad and then reprising their Grammys duet with a snippet of his hit "Your Song," during which he improvised the line, "I hope you don't mind that I wrote down in words/ How wonderful life is with Gaga in the world."

The gothic-themed event took place at a Windsor mansion owned by John and partner David Furnish and featured performance artists wearing straightjackets and dangling from fake trees and bandaged men in white coats serving cocktails in medicine bottles. According to reports, guests included Elizabeth Hurley, Kate Beckinsale, Sharon and Kelly Osbourne, Jon Bon Jovi and Kid Rock.

What do you think of Gaga's new song? Let us know in comments below.