The hosts are also nominees but the big competition this year is from country veteran Keith Urban, who leads with seven nominations. As proven by their harmonies, the country stars were totally in sync on stage - something that will serve them well when the ACMs take place just a few days after their Late Show performance.
If you don't have an account yet, you can sign up for a free 7-day trial to watch the show tonight.
The special will be broadcast live from T-Mobile Arena in Las Vegas Sunday, April 2nd live from 8-11 pm ET/delayed PT on the CBS Television Network. CBS will live stream the ACM awards this year.
While promoting the upcoming ACM Awards, Luke Bryan and Dierks Bentley treated "The Late Show With Stephen Colbert" audience to a Merle Haggard cover!
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"To be a female in country music right now is such a attractive thing, I think", Ballerini says. If you want to watch the ACM Awards online, just check out the pre-show at ACMawards.twitter.com.
Calling all country music fans and singers! They'll both perform live, along with Miranda Lambert and other artists.
Cole Swindell will perform with Bentley on their song "Flatliner".
He's up against Luke Bryan for Entertainer of the Year.
Underwood is, of course, also nominated in the Female Vocalist of the Year category, alongside pal Lambert, Ballerini, Maren Morris and Kacey Musgraves.