Grimes had a major moment on Monday, May 6: The critically beloved, up-and-coming musician attended her first-ever Costume Institute Gala at the Metropolitan Museum of Art in NYC. And the "Oblivion" producer and singer (real name: Claire Boucher) had none other than Chanel's Karl Lagerfeld dressing her.

"It was kind of insane [meeting Lagerfeld]," Grimes, 25, says in an exclusive video, shot a few days before the Met Gala. She and the legendary designer first got acquainted at a fashion show in Paris -- where he quickly sized her up. "He was looking up and down and said 'fresh,'" Grimes recalls as she hangs out in the Chanel headquarters. "I don't know if that was good or bad!" she adds, laughing.

Trying on the iconic fashion house's footwear, accessories and other pieces, the Canadian artist -- who released her third album Visions, to critical acclaim last year -- says she's humbled to don the label at such a high profile event.

"It's a pretty big honor to be wearing Chanel to the Met. It's so imaginative and diverse. It's classical in the most adventurous way."  And it sounds like Grimes had a great night! "I saw both Kanye and Blondie play last night, not a bad lineup indeed," she wrote to her nearly 138,000 followers on Twitter.

Watch Grimes get prepped for one of the biggest nights in fashion and pop culture now!

Click here to view the live stream (+ archived version) of the 2013 Met Gala on