Tim McGraw, daughter Gracie McGraw sing duet

Tim McGraw and daughter Gracie McGraw treated fans to a surprise duet over the weekend.

The 48-year-old country star and his 18-year-old daughter performed the new song "Here Tonight" at his concert Saturday in Nashville. Fan videos of the father-daughter duo singing subsequently went viral this week.

Hill also joined McGraw on stage to perform their 1997 duet "It's Your Love." The song is the lead single on McGraw's fourth studio album, Everywhere, and was nominated for Best Country Collaboration at the 1998 Grammy Awards.

McGraw and Hill married in October 1996, and also share 17-year-old Maggie and 13-year-old Audrey. The singer previously admitted to People, "You never feel like you are doing everything right as a parent, especially when you have daughters. I dread the first broken heart!"

McGraw kicked off his Shotgun Rider tour in June following Gracie's high school graduation, and will bring the tour to a close Sept. 19 in Irvine, Calif. The country star last released Sundown Heaven Town in September 2014, and will debut his 14th studio album this year.