“The Voice”‘s season 21 contestants are getting some help from Mega Mentor Ed Sheeran in the Knockout Rounds, and even the Grammy winner is impressed by their mesmerizing musical talents!

Ed joined up with longtime friend Ariana Grande on Tuesday’s show to help coach her latest pairing, Ryleigh Plank and David Vogel. While Ryleigh wowed with her powerful vocals on Miley Cyrus’ “Midnight Sky,” it was David’s stripped-down rendition of Selena Gomez’s “Lose You to Love Me” that had Ed and Ari sitting up straight in rehearsals.

“That’s so good,” Ed marveled. “You’re making it like a stadium anthem, with an acoustic guitar. It’s really, really cool… I wish I had notes to give you, but I don’t.”

After asking David about his guitar tuning, Ed continued to gush about the rendition “I have not heard that song sung in that way. The chords that he was using, the fact that it was open tuning — that’s me geeking out for a second. I am a fan.”

“This is such a vulnerable song,” Ari added, noting that it was her favourite performance of Vogel’s so far in the competition. “I think this is so special and intimate.”

When it came to the stage performances, Ariana was aghast at the decision ahead of her, joking with her fellow coaches, “Is it too late to quit?”

Ultimately, she chose Ryleigh as the winner of the Knockout to move on to the season 21 live shows — “I think she’s one in a billion,” Ari praised — however, David also got a ticket to the lives after a steal by John Legend!

“David adds something different to my team — we have no one that sounds like him,” John raved. “I think Team Legend just got a bit stronger.”

Last week, a source told ET that Ari has been loving her first season on The Voice so far.

“She has looked up to the coaches for a while and she and Kelly have really formed a strong friendship,” the source noted. “Ariana loves that this allows people to see her talents beyond her singing — she’s a writer and producer, and very knowledgeable about music. [She] is also having fun and loves joking around with the coaches.”

As the Knockouts continue, check out ET’s complete roundup of the season 21 team rosters to follow along with your favourites.

“The Voice” airs Mondays and Tuesdays at 8 p.m. PT/ET on NBC. See more in the video below.

MORE FROM ET:

‘The Voice’ Season 21: Watch All of the Knockout Performances!

‘The Voice’: Girl Named Tom’s Song For Their Dad Brings Kelly to Tears

‘The Voice’: Ariana Grande and Ed Sheeran Catch Up on Married Life