Video: Adele post surgery, she sings a capella for CBS 60 minutes.

WorldWide Tech & Science. Francisco De Jesús.

Adele sings a cappella for Anderson Cooper

When Adele performs at the Grammys on Sunday night, in front of an expected audience of 25 million, she knows that many will be expecting her voice to falter. After all, it was only four months ago that she underwent vocal cord surgery.

But Adele herself isn't worried about the health and strength of her voice, as she proves to Anderson Cooper in this "60 Minutes Overtime" video.

To hear "Rolling in the Deep" in concert is exciting; to hear it a cappella is extraordinary. That's how Anderson heard it during his recent interview with the young singer for "60 Minutes," and when we spotted this scene in the raw footage, we knew we had to share it.

This clip is the first time Adele's voice has been heard publicly since her surgery, and we think it's a safe bet that she'll do just fine this Sunday on stage.

To see the full "60 Minutes" profile of Adele, reported by Anderson Cooper and produced by John Hamlin, tune in on Sunday, Feb. 12 (7:00-8:00 PM, ET/PT on CBS) before the Grammys.

British sensation Adele knows that when she opens her mouth to sing at the Grammys this Sunday, just months after vocal cord surgery, many will be wondering if her voice will hold up. Hear what Adele herself had to say about those worries when she sat down with Anderson Cooper for an interview that airs on the "60 Minutes" broadcast this Sunday, Feb. 12 at 7 p.m. ET/PT.