SAN FRANCISCO--Toward the end of Leslie Feist's set Tuesday night at the Fillmore, a woman in the crowd screamed, "I love you!"

A common occurrence at a concert, sure, but in this case, the accolade was well deserved and the feeling certainly seemed mutual.

In two sold-out Fillmore shows, the much-lauded Canadian singer-songwriter conveyed a genuine love of performing and for her audience that resonated to the very back of the venue. She also showed a rare, almost vaudevillian playfulness, whether it was bringing up one of her friends to tap dance along to "Let It Die" or dividing the audience based on shoe style (rubber, wood, and leather) and guiding them in an enthusiastic three-part harmony on "So Sorry."

Brooklyn-based indie rock quartet Grizzly Bear kicked off both nights with a collection of lush, dreamy arrangements taken primarily from its latest release, 2006's Yellow House. The band's lineup has expanded since Edward Droste started it as a solo project in 2003 and now includes multi-instrumentalists Daniel Rossen, Chris Taylor, and Christopher Bear.

Grizzly Bear's sound soothes the senses with crystalline guitars, soaring four-part harmonies, and expansive compositions laced with flute, clarinet, and zither. The four-piece served as a near-perfect precursor to the night's star.

Under a canopy of Christmas lights that recalled a summertime backyard party, Feist took the stage Tuesday night and immediately charmed the audience by looping vocals to harmonize with herself on "Honey Honey" from The Reminder, her latest release. She used this technique to great effect several times during the performance, even looping layers of whistling for a sweet, birdlike sequence on "The Park," whose plaintive lyrics centered on Feist's recurrent theme of love and loss: "Why would you think your boy could become / the man who could make you sure he was the one?"

But the songs' often-melancholy tones belied Feist's disarming sense of fun onstage. The multi-instrumentalist is known for bringing her audience into the act, and this was the case on multiple occasions tonight. She often conducted the crowd midsong, giving them ample opportunity to sing along on songs like the recent single "One Two Three Four," for which she donned a sequin sleeve in a nod to her sparkling outfit from the song's much-blogged-about video.

The jazzy, synth-laden grooves of her 2004 breakout album Let It Die were stripped down and much closer to the guitar-oriented sound of Reminder. Ultimately this difference didn't matter, though, because Feist's easy, accomplished guitar playing and wistful, sultry voice made the arrangements engaging in their own right. The show's pace was well-crafted, too, alternating moods between relaxed ("The Limit to Your Love") and upbeat ("I Feel It All").

The topper on both nights was Feist's cover of Nina Simone's "See Line Woman," dubbed "Sealion" on Reminder. Although all of Grizzly Bear joined Feist for a foot-stomping rendition Wednesday night, it was Tuesday night's version that elicited the aforementioned declaration of love. In response, Feist gave another of her many endearing, self-effacing laughs and offered a brief anecdote.

"I saw Janet Jackson when I was 13," she began, "and when she told the audience 'I love you, too,' even then I was cynical enough to think, 'that's such a lie!' Tonight, though, I do feel what could be considered love for you all."

Amid the storm of cheers that ensued, even a cynic would believe her.