Joey + Rory are up against stars like Blake Shelton in the category.
Rory and Joey Feek are "still smiling" over their surprise GRAMMY nomination.
"When you love country music as much as we do, to even be nominated for a Grammy for Best Duo/Group Country Vocal Performance is like winning the lottery," Rory tells ET.
WATCH: Rory Feek Details Wife Joey's 'Excitement and Tears' After Learning of GRAMMY Nomination
The couple is nominated alongside Blake Shelton and Ashley Monroe; Charles Kelley, Dierks Bentley and Eric Paslay; Brothers Osborne; and Little Big Town.
"Those artists are stars -- at least to us, they are," Rory says. "Joey and I feel like we're just regular folks -- the kind that buys and listens to those artists' records. So to be nominated for an award like this with them is such an honor."
The GRAMMYs ceremony is set for Feb. 15 in Los Angeles, just two days before the couple's daughter will celebrate her second birthday. It's fitting, since their daughter, Indiana, stars in the video for their GRAMMY-nominated song, "If I Needed You."
"I made the video right after Indy was born as a way to share this special gift that God had given us with others," Rory says. "I still watch that video all the time. It's not a music video, it's a piece of our life set to music. Most all of our videos actually are. This one is just the most special because our little Indy was the guest star!"
WATCH: Rory Feek Has 'No Desire to Go on Singing or Performing' Without Joey
The career milestone comes at a bittersweet time for the family, as Joey continues bravely battling cancer. In recent updates on his blog, This Life I Live, Rory has admitted that his wife's condition continues to "decline." He recently wrote, "I'd like to tell you that she's doing great and is going to beat this thing. But I can't."
Meanwhile, Joey + Rory are set to debut their latest album -- Hymns and Stories That Are Important to Us -- on Feb. 12.
"This is the last record that Joey and I will ever get to make and the last songs we'll ever get to sing together," says Rory. "I have no desire to go on singing or performing without her."
WATCH: Blake Shelton Calls Rory and Joey Feek 'Inspirational'
Outside of performing, Rory is a well-known songwriter, penning hits like "Some Beach" for Shelton and "A Little More Country Than That" for Easton Corbin, among others.
"When I first moved to Nashville, I was fortunate to get to spend a lot of time and write a couple of songs with the late, great Waylon Jennings," Rory recalls. "At his house, on his end table, he had a GRAMMY Award. I remember being in awe of him and the award, thinking that a GRAMMY was something that was too far out of our reach.
"I'm sure both Joey and I, through the years, have thought to ourselves, 'Wouldn't it be wonderful if…?' But honestly, we've not dwelled on it," he continues. "We've always taken the approach to just do what we do in the most honest way we can, and believe that good things will come of it. I'd say this is one of the very, very, very good things!"
They may be competitors at the GRAMMYs, but Shelton had no shortage of kind words for the couple when ET caught up with him in November. See the interview below.