"We did our rehearsal today and we did a game time call on whether we did sing the track or lip sync it and I decided to lip sync it because the voice is just not there and you want to represent country music the best you can."
Brooks admitted he and his wife, Trisha Yearwood, are "exhausted" after spending the last two years on their world tour, even performing two shows a night on some dates.
He told E! News: "It's been 400 shows and we're all exhausted, but having the time of our lives."
Fans took to Twitter to express their disappointment.
Ahead of his performance, Garth praised Ask Me How I Know writer Mitch Rossell, a 29-year-old singer-songwriter who moved to Nashville from Chattanooga, and joked about his nerves at appearing at the prestigious ceremony.
He said: "['Ask Me How I Know'] is the first thing he's ever had cut and recorded. He's a songwriter that moved here with nothing but a dream, so we all decided to bring him up with us, and he's playing with us. He's a little nervous right now, because he's just a kid, and he's just starting out, but he's the sweetest guy in the world...
"You see his face and he's scared to death right now, and we're enjoying every second of it."
- Bang! Showbiz
