Tim McGraw Covers Luke Bryan's 'Do I' Backstage After Thunderstorm Delays Show

Rich Polk/Getty Images for iHeartMedia
Tim McGraw poses backstage during the 2015 iHeartRadio Country Festival at The Frank Erwin Center on May 2, 2015 in Austin, Texas.

How does Tim McGraw pass the time when a thunderstorm delays his show? Singing Luke Bryan, of course.

McGraw was set to perform in St. Louis on Sunday night (Aug. 9) when a massive storm kept him offstage for a couple of hours. So, the singer took the sudden free time to sing some throwback Bryan.

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The 48-year-old country star -- who looks about half his age in the video, showing some seriously muscular arms in a tight tank -- croons while his band uses everything from an electric guitar to a violin to bring Bryan's "Do I" to life.

McGraw has recently begun singing covers backstage in various cities, including Chicago's "Hard to Say I'm Sorry" when he hit the Windy City, and Lynn Anderson's "Rose Garden" in Cleveland as a tribute to the late singer. He gave a shout-out to Bryan on Twitter, announcing that he chose "Do I" to honor his fellow country singer's "big week" (Bryan just released his fifth studio album, Kill The Lights, Aug. 7).