For the first 'The Voice' Knockout Round on Monday night (Oct. 27), coach Blake Shelton paired Griffin with James David Carter, but not without a mentor session from Taylor Swift. After the two battled, one singer went home.

Neither team member knew they'd be lucky enough to get to chat music with Swift, so they both got the surprise of a lifetime. “It was really cool to walk in and see Taylor,” Carter revealed. He explained how and why he enjoys country music, before letting Shelton and Swift know he'd be singing his own version of James Taylor's 'You've Got a Friend.'

Carter performed the song for the 'Shake It Off' starlet during practice, and she seemed really pleased, saying he did an amazing job "delivering [the] sentiment." Swift also loved his riffs, calling them "cool."

Meanwhile, Griffin -- originally a member of Team Pharrell -- tried his hand at Justin Bieber's 'As Long as You Love Me.' “I chose this song because it’s a really catchy pop song,” he shared. Shelton agreed it was a good choice for him, since he can make it really reflect himself. Swift helped with that by giving the contestant tips and even telling him how to increase his performance with a simple hand bob. Shelton said that alone changed the cover.

For Carter's rendition of 'Friend,' he added something extra with his acoustic guitar. Shelton wasn't sure he could pull the song of, but told him afterward: "Imagine my surprise. You definitely made that song your own." He also commended him for following Swift's advice onstage when he expected him to chicken out.

In the end, Shelton went with Carter as the winner. Sadly, Griffin had to go home, but not without thanking his coach. “Blake thank you so much for stealing me," he told Shelton before ending his time on 'The Voice.'

Watch Griffin Sing Justin Bieber's 'As Long as You Love Me'