Are you ready for some football? Country singer Carrie Underwood is, as she will once again be the voice behind NBC's  game of the week "Sunday Night Football" opening song.

On Thursday night Underwood stopped by "The Tonight Show With Jimmy Fallon" to talk about the process behind recording the opening theme"Waiting All Day for Sunday Night." Fallon asked her how many times she had to record the theme because there's different teams playing each week.

"I go in and I record the main bass version and then they cut and paste," Underwood said. "So you record the whole song and you leave out who is playing who," Fallon added.

Underwood said some teams are harder than others because they'll thrown in names of players on the teams, but she has no problem with the names Rodgers and Manning in the song. When Fallon asked about the Pittsburgh Steelers' Ben Roethlisberger, she said "That one is impossible to do."

You can watch the full video below:

In an interview with WIN 98.5 in Battle Creek, Michigan, Underwood said she's had the opportunity to meet several NFL players over the years during the shoots.

"I got to hang out a bit with Andrew Luck and Antonio Brown . I've met other players in the past season. Everyone's just so nice," Underwood said. This is her third season singing the show's theme.

NBC Sports released a behind the scenes video of the opening song in August. It showed several NFL stars, including Clay Matthews, Odell Beckham Jr., Dez Bryant,and Russell Wilson on set, as well as the live audience Underwood plays to during the shoot.

"It's always fun to be a part of 'Sunday Night Football' and recording the open," Underwood said in the video.

The "Sunday Night Football" opening premieres on NBC this Sunday, Sept. 13, at 8:20 p.m. EDT.