Carrie Underwood sang an a cappella version of "We are the Champions" with Jimmy Fallon and The Roots in honor of Super Bowl XLIX.

The 31-year-old singer, 40-year-old television host and "The Tonight Show" band performed the song with Sam Smith, Ariana Grande, Blake Shelton, Meghan Trainor, Usher, One Direction and Christina Aguilera to open the post-game episode.

Will Ferrell and Kevin Hart later appeared on the program to lip sync battle with Fallon. The trio lip synched renditions of "Drunk in Love," "Since You Been Gone" and "All of Me" at the Phoenix Orpheum Theatre.

The former "American Idol" winner kicked off the NFL event with a special version of her Sunday Night Football theme song, "Waiting All Day for a Super Bowl Fight." The singer declared herself "so honored to have been a small part it" Sunday on Twitter.

Underwood released her fourth studio album, Blown Away, in May 2012.

The record debuted at No. 1 on the Billboard 200, and includes the singles "Good Girl" and "See You Again."

The singer released a music video for new song "Little Toy Guns" on Saturday.