By Whitney Pastorek
Updated December 20, 2019 at 10:28 AM EST

Here is why you must tune into the Grammys on Sunday: Radiohead is playing “15 Step” with the USC marching band. I’ve been told it’s okay to talk about this now (somebody else already leaked it), and how I wish all of you could have been here at Staples with me this morning to watch Thom Yorke, Jonny Greenwood, and three dozen elated college kids take an already very good song and turn it into a jubilant, slightly menacing masterpiece. We’re talking “I would pay money to buy that off iTunes” good. “I will keep that performance on my DVR to watch on sad days” good. “Please make the song into a vacation resort because I want to go to there good.” It is so. cool.

When I walked in at 9 a.m., there were already tubas glinting under the shiny, American Idol-style metal gridwork of the space stage, the thunder of the rhythm section bouncing around like buckshot. They did a rough run-through with crew and directors clustered on stage, after which Yorke politely asked, “Can you make my voice sound a little less shiny? I like the idea that I’ve got to belt it out over these guys, you see.” Between takes, he beatboxed a bit into the mic; the band kids sat on the risers and mostly just grinned in disbelief. Yorke wandered down to the lip of the orchestra pit and asked a nearby stage manager, “Is it okay if I stand here?” Sure, said the guy, “but just so you know” — he gestured to the floor beneath Thom’s feet — “this is a wall that comes out of the ground.” Thom took a step back. “All right! Here we go! Standby!” said another stage manager, and the wall did indeed come up. The band members stirred with excitement. A stand-in who was not Gwyneth Paltrow began reading the intro off the teleprompter, and by the time she got to “Nominated tonight for Album of the Year…” the wall had lowered again to reveal Thom making a my-head-is-exploding gesture to Johnny, I assume because even Thom Yorke still gets jazzed about the Grammys. And then a snare drummer in the front row counted things off, the bass players raised their sticks, and the awesomeness began.

After the jump, I talk to one of the USC students, and run down rehearsals from Carrie Underwood, the Jonas Brothers (with Stevie Wonder!), Taylor Swift, and Miley Cyrus…

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Mad props to the USC kids for their talent and their stylish choreography, but mostly for being totally professional in a situation that would have reduced many grown men to pudding. Their directors just finished making tweaks to the musical arrangement last night, and tomorrow they’ll be playing with arguably the best band in the world on national TV, yet they completed take after take of the complicated rhythms with incredible poise. “Ecstatic” is how 19 year old Kelsey Anderson (communications major; bass drum) summed up the feeling of getting this gig. Her eyes had the slightly glassy look you see in people who have recently experienced a religious conversion, or seen the face of God. “I went out and bought In Rainbows on vinyl for Thom to sign. He wrote my name on it. I’m gonna keep it forever.” She was highly complimentary of the spiky-haired frontman, with whom they apparently had robot dance-offs in rehearsal. “He’s surprisingly down to earth, fun, and amazing to work with,” Anderson said. “Some people you think might have big egos, but he doesn’t. We we were just in awe of him.” As for whether her life has now peaked at 19, she laughed and said, “This is pretty much the coolest thing I’ve done so far.”

I didn’t envy Carrie Underwood having to follow that lot into the room, but then I remembered it’s a rehearsal, not a competition. Still, the blonde held her own, and you gotta respect a gal who can work a bedazzled microphone and a bombastic song like “Last Name” at 10:30 in the morning. Clearly, the kid wakes up warmed up and able to drill notes that go far above and beyond the soundcheck call of duty, using her patented grip-the-mic-and-crank-it body language to summon her platinum-selling wail from wherever it is housed and get random people in the front row to give her a standing ovation. She nailed the song at full power three times in a row. “She is very loud,” I texted a friend of mine. “It’s because she’s 20,” he texted back. She’s 25, but anyway, you get the point. I like that Carrie went with her Cuervo song instead of that prom queen number she did on the People’s Choice Awards — it’ll balance out Chesney’s choice of sincerity quite well, I think — and I also enjoy her female guitarist, who was up there shredding like Slash, if Slash had a perky ponytail.

Speaking of perky ponytails (bad segue), hey, it’s the Jonas Brothers! And, because it’s already been leaked and CBS said I could tell you, also it’s Stevie Wonder! We were first treated to Stevie’s band working through the instrumentation of “Superstition” — you tell me what song has a better horn melody than “Superstition,” PopWatchers, because I cannot think of one — and then a little “Baby Elephant Walk” to kill time. The house started filling up with tweens who I hoped would not squeal too much when the Best New Artist nominees took the stage (they in fact did not squeal at all), and the stage manager came over the P.A. to instruct everyone to put their cameras away for the closed rehearsal. (Note: there were at least a hundred people in this closed rehearsal.) Stevie materialized behind his keyboards to warm up the vocoder, the JoBros milled around behind their guitars, the stage manager counted down… and next thing we knew, a 22-time Grammy winner was robo-singing the intro of “Burnin’ Up.”

So that means the rumored surprise guest appearance from Michael Jackson isn’t happening (at least in this segment), but, um, Joe Jonas was wearing a red nylon jacket, black pants, and white sneakers as he skipped around the stage, so that’s something. The medley does not sound un-good — I especially liked the way the brothers kept saying “C’mon, Stevie!” as though Stevie needed their encouragement — and it is a high energy three minutes, to be sure, that your teenage daughter will probably very much enjoy and then ask you who was the man in the sunglasses.

They started rolling Coldplay’s road boxes in while Stevie switched over to a gorgeous grand piano to practice a solo take on new song “All About the Love Again” — another chance to note here that sitting around just listening to awesome musicians noodle on their instruments is a damn pleasure — and I sighed at the knowledge that I couldn’t stay to see Chris Martin’s band (or those U2 people) rehearse later. Instead, I ended my afternoon with the cheerful tones of the hottest young misses in the music industry today, Miley Cyrus and Taylor Swift, performing the latter’s “Fifteen.” I have long since given up on wanting more from Swift, and to be totally honest, she is just so pretty and so poised that I found myself unable to do much but sit there and watch her and Miley giggle like the schoolgirls they are as their backing band set up on the circular platform in the center of the room, and wonder how they appear so very not traumatized by their lives. The gals gossiped, they blew kisses, they jammed around with Taylor on acoustic 12-string, and when the mics got turned on, they sang the song in a pleasant and relaxed manner. It was by no means extraordinary — Swift’s guitarist did most of the harmonizing — but they’re not going to embarrass themselves, either. I’ve come to the conclusion that for some reason, they both do their best work while sitting down. And sure, neither one of them is nominated for anything, but the Nielsen ratings won’t care. Hey kids! Buy Stevie Wonder records!