Florida Georgia Line once again reached across genre lines when they teamed with John Legend for a joint performance at the 2017 Billboard Music Awards on Sunday night (May 21).

The country duo of Tyler Hubbard and Brian Kelley joined Legend for a live collaboration on their mega-hit "H.O.L.Y.," which reached No. 1 when it was released as the single from FGL's most recent album, Dig Your Roots. Legend started the performance with his own love song "Surefire."

The soulful singer sat alone at a piano before additional players joined in slowly. An arena full of fans with their phones lit up set the mood for FGL to join in, and they soon did. Legend kept playing as Hubbard and Kelley started their enormous hit song.

The performance was not of the type fans are used to seeing from FGL on television. In fact, if you just knew the band through awards show performances you'd mostly think they were a fire-starting mix of pop, hip-hop and country. This song shows their sensitive side — both men let their wives co-star in the music video.

Legend took the second verse before Hubbard and Kelley worked through the final chorus. At the end they thanked one another. There was little time for applause before the show's next segment.

See FGL Walk the Red Carpet at the 2017 Billboard Music Awards

Florida Georgia Line were the most-nominated country artist at the 2017 Billboard Music Awards, earning nominations for Top/Duo Group, Top Country Artist, Top Country Album and more. The won the award for Top Country Song for "H.O.L.Y." earlier in the ABC broadcast.

The duo are set to hit the road over the summer for their 2017 Smooth Tour, on which Chris LaneRyan Hurd, Russell Dickerson and Morgan Wallen will serve as support acts, with Nelly also joining them on the bill and the Backstreet Boys appearing on select stadium dates. The tour kicks off June 2 in Austin, Texas, and runs through Oct. 21 before wrapping up in Georgia.

See More Pics from the 2017 Billboard Music Awards