The competition is heating up on The Voice Season 21, and Monday (Oct. 25) brought the first night of the Knockout Rounds. Winding down to the final minutes of the two-hour program, Team Kelly's Girl Named Tom went up against the talented Holly Forbes, showcasing their stellar sibling harmony on Glen Campbell’s “Wichita Lineman.”

Before their performance, the band — Joshua, Bekah Grace and Caleb Liechty — explained why they chose the classic country song: “It’s a song about a really hard-working man, and we relate to this song because [our dad] is a pretty stubborn man,” Caleb told both Clarkson and the season’s mega-mentor, Ed Sheeran, in rehearsals. “But he’s got this hope.”

“Our family has gotten a lot closer because our dad was diagnosed with terminal cancer,” Bekah Grace added. “He has such a positive attitude going into every doctor’s appointment. It’s been huge for us to see that.”

The family trio out of South Bend, Ind., floored the coaches with their version of the Jimmy Webb-penned hit. Their sibling harmonies were nearly flawless and provided listeners with a heavenly take on the classic tune.

Forbes, who earned a four-chair turn with her blind audition performance of Elton John’s “Rocket Man,” also blew the coaches away with a rousing rendition of “Superstar” by the Carpenters. Her take on the song sparked an instantaneous positive reaction from judges Ariana Grande and John Legend.

Clarkson knew both artists were promising winners in the competition, but she had to go with her gut, and admitted she had a strategy she was working with. She ultimately picked Girl Named Tom as the winner of the Knockout Round.

However, even though Forbes didn’t win over Clarkson with her performance of "Superstar," she ended up getting her pick between Legend and Grande due to a double steal. Forbes will now head into the live shows representing Team Ariana.

The Voice returns Tuesday (Oct. 26) at 8PM ET on NBC.

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