When Dolly Parton asks you to sing, you sing. That’s exactly what Kelly Clarkson did during her Las Vegas residency—delivering a powerful, emotional rendition of “I Will Always Love You” at Parton’s personal request. “You do one of the best versions I have ever heard,” Dolly commented, adding, “Whitney and I would both be proud.” Click to watch the performance that pays tribute to two icons—and proves Clarkson’s voice is right at home among legends.