Jimmy Fallon's always down for a good prank!

Ahead of The Voice's season 24 Playoffs, the late-night host decided to get some laughs by planting himself in the audience of the NBC singing competition and having some fun with coaches Reba McEntire, John Legend, Gwen Stefani and Niall Horan.

Donning a long gray beard and mustache, Jimmy interrupted host Carson Daly as he did his intros to the upcoming episode.

"Is this the part of the show where you take questions from the audience?" Jimmy asked in a deep voice.

"We don't really have that part of the show," Carson replied, but Jimmy was undeterred.

"I wanted to know if the winners of this show get to go on The Tonight Show Starring Jimmy Fallon," he said, earning big laughs from the audience members seated around him. "'Cause that's a quality program. He's a good guy."

Jimmy then took the stage to perform an earnest rendition of Tony Bennett's "(I Left My Heart) In San Francisco" -- a tribute to the late crooner that got some of the coaches genuinely emotional, with John, Gwen and Niall even admitting that they would turn their chairs for Jimmy's voice during the Blind Auditions!

Finally, Jimmy had one question that many Voice fans have been wondering this season, asking Gwen what time her hubby, Blake Shelton, would arrive.

"Never, it looks like!" Gwen laughed.

Watch the funny moment below:

ET spoke with Gwen ahead of this season's Battles, where she opened up about how surreal it is to return to The Voice without Blake by her side. The Cowboy departed the NBC singing competition earlier this year, after 23 seasons.

"It feels kind of like [my] first season, before I knew he existed," she shared. "It's kind of weird, but it's also like, I'm having so much fun."

"Like, I'm only here because it's fun," Gwen added. "The coaching and actually getting to know your team after the Blinds is my favorite thing, 'cause it's like, the dream's there."

She admitted, however, that it is a little nerve-wracking to look to Blake's chair and instead see The Voice's newest coach -- the Queen of Country herself.

Of how Reba's handled her first season so far, Gwen recalled the Blind Auditions with a laugh.

"She did great. She didn't have to do anything," she remembered. "She'd be like, 'I think you were great. I'd love to have you on my team,' and then they'd be like, 'I pick you!'" 

The Voice airs Mondays at 8 p.m. PT/ET and Tuesdays at 9 p.m. PT/ET on NBC.

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