The Band Perry Surprise Taylor Swift’s 1989 World Tour Crowd in Indianapolis, Sing ‘If I Die Young’ [WATCH]

Taylor Swift's latest 1989 World Tour special guests: none other than the Band Perry, who joined the country-turned-pop superstar onstage in Indianapolis, Ind., on Wednesday (Sept. 16) to perform their very first hit, "If I Die Young."

"I want to remind you that anyone you see on the 1989 Tour, coming out to surprise the audience, they're doing it for free, out of the goodness of their heart, because they wanted to come play for you and surprise you," Swift told the crowd before introducing the country trio. "And any guest on the 1989 Tour stage had the opportunity to surprise any crowd at any show, and they chose you, Indy ...

"Something I'm very proud of is that I came up in country music -- really proud of it -- and I still am such a huge fan of country music, and, in my opinion, the people I'm about to bring out are some of best musicians, some of the best things we've got going in country music," the singer continued. "And they have won Grammys and CMAs and ACMs; they are unbelievable. Country music is all about family. They happen to be a family ..."

With that, Kimberly, Reid and Neil Perry emerged from the back of the stage and joined Swift at four microphone stands set up at center stage. As Kimberly Perry began the first lines of "If I Die Young," she was drowned out by the crowd. Swift and Perry's brothers provided harmonies, and Swift took the lead on the second verse. Press play on the video above to watch a clip of their performance.

"If I Die Young" became TBP's first No. 1 hit after its release in 2010. It has been certified six times platinum and won two CMA Awards, for Single of the Year and Song of the Year.

"Dear @TaylorSwift, thank you for a magical night," the Band Perry writes on Instagram, along with a selfie of the four of them. "Dear Indianapolis, thank you for a magical sing-a-long. We love you."

TBP are the fourth country act Swift has shared the stage with on her current tour. The Dixie Chicks‘ Natalie Maines sang "Goodbye Earl" at one of Swift's Los Angeles stops in late August, Sam Hunt performed “Take Your Time” at a mid-July show in Chicago, and during a June concert in Pittsburgh, Little Big Town came out to perform “Pontoon.”

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