The "Wrecking Ball" singer joined the TV host on Thursday's Tonight Show, and the pair went head-to-head trying to guess a random song as the show's band The Roots cover the tune, playing it one instrument at a time and layering it together as it slowly becomes clearer.
As it turns out, Cyrus and Fallon found themselves struggling to buzz in quickly as the game began. Fallon got the first point, correctly guessing The Root's instrumental cover of Joan Jett's "I Love Rock 'n' Roll. He then rubbed salt in the wound by beating Cyrus to the punch in guessing their cover of Bob Marley's "Could You Be Loved."
Cyrus came back swinging though when she guessed the next two songs in a row -- Carly Rae Jepsen's "Call Me Maybe" and then Dolly Parton's "9 to 5" -- making the fifth song of the game a tie-breaker that could tip the scales.
That song was Cyrus' own 2009 hit single, "Party in the U.S.A.," and yet it still took the 26-year-old songstress an embarrassingly long time to recognize the tune as The Roots covered it brilliantly.
Cyrus excitedly beat Fallon to the buzzer, the host jokingly walked away from his podium in frustration.
"It took you that long to get that one?" Fallon asked, jokingly. "I wish I had a no. 1 song they could play."
"That I don't even recognize?" Cyrus responded, poking fun at herself.
While Cyrus led in the points, the game's arbitrary rules dictate that the final song of the challenge is worth 10,000 points, making everything else null and void -- and it was truly surprising how fast Fallon was able to guess Biz Markie's "Just a Friend" for the win!
After the game, Cyrus joined Fallon for a sit-down, where she talked about her recent collaboration with Mark Ronson on the single "Nothing Breaks Like a Heart," and announced the impending release of a new song, which dropped online at midnight, while Cyrus was chatting on the show.
The pop star's new song is a cover of the John Lennon classic "(Happy Xmas) War Is Over," which she recorded with Ronson and Sean Ono Lennon -- the 43-year-old son of the Beatles icon and Yoko Ono.
"[Ronson and I] made a lot of our music at Electric Lady, here in New York," Cyrus told Fallon, referring to the famous recording studio where Lennon and a score of other renowned artists recorded some of their biggest hits. "So we went to Electric Lady with Sean Ono Lennon, and we got to cut 'War Is Over,' and we're also doing it on SNL."
"We wanted to do a Christmas song and I don't think anything could speak louder about what's going on right now than "War Is Over," she shared.
The singer also gushed over getting to collaborate with Sean, sharing, "He's just such an incredible being to be in the room with, because that magic just radiates. I've always loved John and Yoko -- I'm such a big Yoko fan -- so it's just been amazing to work with him."
"His voice is so special, but I think more than just inheriting the voice, or the way he looks, it's about the magic that he has," she added. "And I think that's what he's inherited more than anything, is just this radiant magic."