The Before He Cheats star took to Instagram on Wednesday (06Apr16) and posted a video of the country icon saying, "I'm gonna send this out to my sweetheart, my girlfriend Carrie Underwood. Carrie, a little song for you."

Garth then launches into an acoustic version of his hit song The River, before welcoming Carrie's beau Mike Fisher, a professional ice hockey star, onstage. He joins Brooks for the song, and at one point, even harmonises with the star.

Carrie wrote the caption, "How is it that my hubby, @mfisher1212 gets to sing with THE @garthbrooks before I do?"

She jokingly added, "As payback, I think I'll try to see if (hockey legend) Wayne Gretzky wants to play a pick up hockey game sometime!"

This isn't the first time Carrie has highlighted her husband's surprisingly impressive vocal skills on social media - in January (16), the former American Idol winner posted a video of Mike singing Brooks' The River while driving in their car.

She wrote, "#IAlwaysWantedToMarryGarth. @mfisher1212 duet coming coon..."

After Carrie posted the clip, she told Country Countdown USA, "I said (to Mike), 'You cannot sing with Garth Brooks before I do!' When I was 10 years old I met Garth Brooks and said, 'If you ever need someone to sing a duet with you, I'm your girl.'

"So I’ve been waiting for that forever. And my husband who's a hockey player is gonna sing with Garth? I don’t think so! I might cry if that happens."