Grammy Awards 2015: What to Expect From Tonight's Show

— -- The Grammy telecast this evening will be all about those "Grammy Moments" -- musical mash-ups featuring odd collections of artists that you won't see anywhere else.

The show's executive producer, Ken Ehrlich, says there are so many of these this year, he really can't pinpoint which one people will be talking about on Monday morning.

"This year, that might be the hardest question," Ehrlich told ABC News. "I mean, this show runs the gamut ... you've got AC/DC, Madonna, classic artists like that, and then it's Ariana Grande and Ed Sheeran ... and these combinations this year, I think, are remarkable, all the way from Gwen Stefani and Adam Levine to Rihanna, Kanye West and Paul McCartney."

Not only that, but Ehrlich says a real thrill for him this year is that so many artists who'll be performing have never before graced the Grammy stage.

"At least half the show or more are people who have not been on the Grammys before," he said. "I mean, we've got our standard-bearers. John Legend, we love having back. Madonna's been on a number of times. Kanye's been with us a certain number of times. But I mean, I've got AC/DC on the show! They're not a new, young act, but they've never been on a Grammy show. So the idea of having these first-timers is really exciting, and it energizes all of us."

Here are just some of the stars who've been announced as performing:

Solo: Madonna, AC/DC, Ariana Grande, Katy Perry, Usher, Pharrell Williams, Sia

Together: Lady Gaga & Tony Bennett; Rihanna, Paul McCartney & Kanye West; John Legend, Common and, reportedly, Beyonce; Sam Smith and Mary J. Blige; Coldplay's Chris Martin and alt-rocker Beck; legendary crooner Tom Jones and Jessie J; Adam Levine and Gwen Stefani; Hozier and Annie Lennox; and Ed Sheeran, John Mayer, The Roots' Questlove, jazz icon Herbie Hancock and legendary British rock band ELO, led by Jeff Lynne.

It's an impressive list, but Ehrlich admitted there's one big act that got away from him this year.

"We had some serious talks with U2 and they were ready to come," he said. "Whether it would have been a mash-up or whether it would have just been a solo performance by the band, we were talking. But then that kind of went by the wayside when Bono had his accident."

The U2 frontman hurt himself pretty badly while bike-riding in New York City last November, and has said he may never play guitar again, but Ehrlich hears he may be on the mend.

"I'm hearing really good reports about him being much better, but unfortunately not in time for us," he explained.

As for the acts he has booked, Ehrlich said he's very excited about Hozier and Annie Lennox, who will duet on Hozier's Grammy-nominated hit "Take Me to Church" and Annie's rendition of the 1956 rock song "I Put a Spell on You."

"I think it's gonna be a showstopper," he promised.

Ehrlich also teased that "Chandelier" singer Sia's performance will be one to watch, since the Grammy-nominated Australian singer/songwriter won't pose for publicity photos, doesn't appear in her own videos and won't show her face when she performs.

"It presented some challenges in terms of how we're gonna present her, but I think when people see it they're gonna be knocked out," he said.

But despite all the star power on stage, Ehrlich says the Grammys are still about the little golden gramophones that some lucky artists will be taking home at the end of the night.

"I think one of the things about this show is that I think people really do care about who wins Grammys," he said. "And I certainly know the artists care. So, you know, it makes it a more interesting show. There's a story to it, in addition to these great performances."

The 57th Annual Grammy Awards, hosted by LL Cool J, airs Sunday night on CBS.