'The Voice': Gwen Stefani Tells Taylor Swift Which Sia Hit She Almost Sang Instead

gwen stefani taylor swift the voice
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Stefani and 'Mega Mentor' Taylor Swift teamed up to mentor her team of hopefuls during Tuesday's Knockout Rounds.

Gwen Stefani and the rest of The Voice's season 17 coaches have teamed up with "Mega Mentor" Taylor Swift to coach their teams of hopefuls throughout the Knockout Rounds -- and on Tuesday's episode, the No Doubt frontwoman dropped a major music industry secret.

With decades of experience in the music industry between them, Taylor and Gwen were more than ready to offer advice to singers Jessie Lawrence and Kyndal Inskeep. So far, Gwen's mentorship of Kyndal has almost come at a cost to her romance with fellow coach Blake Shelton.

"I had to block Blake," she admitted of landing the singer to her team. "That could have gotten in the way of my relationship."

However, both Gwen and Taylor were impressed by Kyndal's song selection, Sia's "Elastic Heart," which, as it turns out, was another fated choice.

"This is so weird, because Sia sent me this song for me to do," Gwen revealed.

Taylor was blown away by Kyndal's rendition of the song, which Sia eventually made a mega hit on her own. "That was so interesting -- and not in the way that people say that passive-aggressively," she marveled. "I loved that you stripped it down...your tone is so beautiful."

Gwen agreed, ultimately choosing Kyndal over Jessie to continue on in the competition. "She sings from her heart and she just has so much style to her voice," she told the cameras. "Those are the kind of singers I'm looking for."

Blake recently opened up to ET about how he and his lady love deal with going head-to-head on the competition show this season.

"At the end of the day... it's no different than if Gwen and I were playing cards," he insisted. "She wants to win and I want to win, and that's what they pay us to do on this show, is to try to win."

The Voice airs Mondays and Tuesdays at 8 p.m. ET/PT on NBC. See more about how Blake and Gwen are balancing their relationship with their competitive streak in the video below.

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