We had Las Vegas' MGM Grand Garden Arena covered for the fest's fifth-year anniversary, from the audience to the press room to our backstage video and photo lounge and everywhere in between. (And we'll be there again on Saturday for day two!)
iHeartRadio Music Festival 2015: Watch the Live Stream Here!
Check out all the things you might not have seen during the jam-packed first day, from kickoff to Kanye:
7:01 p.m.: We have our first celebrity visitors to the press room, when Krewella -- DJing an iHeartRadio set at Caesars Palace on Friday night -- roll through to talk about their new music. "With this album, we're starting from scratch with everything. A lot of the songs just start as a ballad. So we're focusing on that, and also experimenting a lot more."
7:29 p.m.: Would social-savvy rapper Travis Mills vote for his idol Kanye West for president? "Yes," he told reporters backstage before the question was even finished. "He's a visionary."
7:43 p.m.: Sam Smith takes the stage to kick off the iHeartRadio Music Festival, and after performing
7:51 p.m.: Smith introduces Disclosure by saying, "These guys completely changed my life when I met them." They start out with "Omen" and then go into their breakout hit "Latch." "Who knows this one?" they joke before the song.
8 p.m.: "Sing this as loud as you possibly can," Smith says before kicking off his final song: megahit "Stay With Me."
8:03 p.m.: Howie Mandel had prime access to the backstage area as Ellen's special correspondent. He pulled off a couple of pranks -- like waking Sam Smith up from a nap by screaming outside his dressing-room door. He did an impromptu interview with Coldplay's Chris Martin seated on the floor (photo above). We heard Mandel tell Martin, "Don't get Jen mad at me" (presumably on/off girlfriend Jennifer Lawrence).
8:30 p.m.: Less than a half-hour later, Chris Martin is on the stage, climbing the bridge connecting the stage with fans during Coldplay's "A Sky Full of Stars" and sings directly to one fan. "I see you," he tells the lucky crowd member while staring deep in their eyes.
8:44 p.m.: Mario is the only artist to leave the press room by dropping the mic.
8:46 p.m.: Shaggy tells reporters about his TV guilty pleasure Love & Hip-Hop: New York: "I love the ratchetness."
8:52 p.m.: Kenny Chesney proves why he's one of the biggest live draws in the country, getting the pop-leaning iHeartRadio crowd crazy for country.
8:53 p.m.: Did Christina Grimmie call her former Voice coach Blake Shelton for some iHeart advice, since he's performing on Saturday night? "I should have, but I didn't!" she tells reporters backstage.
9:06 p.m.: As Chesney closes his set with "Young," he tells the crowd: "I hope y'all have a blast tonight in Vegas. We love y'all for lovin' the music!"
9:18 p.m.: With his deep well of hits to choose from, it might have surprised fans to hear Jason Derulo follow up "Talk Dirty" with the lesser-known song "Trumpets." But one look at the lyrics tells the whole story, since it name-drops two fellow artists on the iHeartRadio bill. "Is it weird that your eyes remind me of a Coldplay song?" and "Is it weird that your ass remind me of a Kanye West song?"
9:23 p.m.: Is Derulo's shirt getting too sweaty? Well then it's probably time to take it off.
9:25 p.m.: Lil Wayne arrives at the venue just 25 minutes before his set and barely makes it to the stage on time. He bolted right after.
9:49 p.m.: Not sure if Lil Wayne's onstage comments will make the radio airwaves or the CW broadcast. "If you have something to drink tonight, put your hands up. If you have something to smoke tonight, put your hands up. If you're f---ing tonight put your mother----ing hands up." And then, to loud screams: "If your p---y stink, be quiet." Got it.
9:53 p.m.: Weezy rolls out one of his most radio-friendly songs "Lollipop" by saying, "This is for the real Lil Wayne fans!"
9:55 p.m.: In addition to fellow iHeart performers The Killers, Duran Duran would also fancy a collaboration with FKA Twigs. "She's got this really weird, freaky kind of thing that I think would work really well with us," Simon Le Bon tells reporters backstage.
10:13 p.m.: Demi Lovato makes a strong first impression by standing with her back to the audience wearing a cheeky leotard as the opening notes of "Cool for the Summer" play.
10:19 p.m.: When Lovato sings "Really Don't Care," she makes a point to take a nice long pause after singing the line "You can take your words and all your lies." Hi, haters.
10:31 p.m.: Lovato does a solid for all the '90s kids in the crowd, bringing out Third Eye Blind frontman Stephan Jenkins to sing "Jumper."
10:40 p.m.: iHeartMedia exec John Sykes greets Lovato excitedly after her set -- complete with mind-blowing hand gestures.
10:43 p.m.: The Killers kick their set off in true Vegas style by performing Elvis Presley's "Viva Las Vegas," complete with the Jubilee showgirls.
11:11 p.m.: Mr. Boombastic himself, Shaggy, hits the stage to run through his hits -- "Angel," "Wasn't Me" and "Luv Me, Luv Me," to name a few -- before playing some new tunes.
11:33 p.m.: Duran Duran hits the stage after an introduction from James Corden. The Late Late Show host could then be seen dancing in the aisles to his favorite Duran Duran hits -- even forming a conga line and making new friends as he shook his moneymaker through the crowd.
11:40 p.m.: "Did they feed you tonight? Or is anybody… hungry?" -- How Simon Le Bon introduces "Hungry Like the Wolf"
12:05 a.m.: In case you've lost count of David Guetta's hits, this set proves it. "Titanium," "Hey Mama," "Play Hard," "Dangerous" -- they're all here. And David has the thankless job of warming up a clearly Kanye-focused crowd.
12:31 a.m.: It's finally Yeezy o'clock. For our full recap of Kanye's set, head here.
--Additional reporting by Keith Caulfield and Shirley Halperin