The Civil Wars sold out the Ryman Auditorium in Nashville last night, and then introduced Taylor Swift for an impromptu live performance of their song 'Safe and Sound' from 'The Hunger Games' soundtrack. Swift has been an early supporter of the Americana-country duo.

After being introduced as a shy and inexperienced songwriter (clearly joking), Swift appeared onstage in a bright yellow dress and gave out hugs like grandfathers give away Werther's Originals. The Civil Wars' Joy Williams and Swift spent a moment remembering the duo's show from 2011, with Swift in the audience.

"I think you bought a T-shirt," William says in the video below.

"I did buy a T-shirt," Swift answers. "I contemplated wearing it."

The trio delivered a beautiful rendition of the song (last week's No. 2 song on the digital singles charts) with Swift and Williams singing over John Paul White's tender guitar picking. The Civil Wars are known for their original harmonies, and Swift fit right in, even matching Williams on notes above her usual register.

According to the Tennessean, the Civil Wars finished the show with more selections from their critically acclaimed 'Barton Hollow' album, as well as a cover of Michael Jackson's 'Billie Jean.'

Watch Taylor Swift and the Civil Wars Sing 'Safe and Sound'

Note: Video has since been pulled.