LAS VEGAS >> Taylor Swift didn’t divulge any more new secrets about her forthcoming album when she took the stage at the iHeartRadio Music Festival in Las Vegas, but the crowd’s enthusiasm about her bouncy new single, “Shake it Off,” seems to bode well for the new record.

Swift, dressed in a bedazzled, bubble gum pink skirt and top, opened for the 4th annual festival Friday with hits including “Love Story” and “I Knew You Were Trouble.” A parade of chart-toppers followed her in the nearly five-hour program, including Coldplay, Usher, Nicki Minaj and Ariana Grande.

The two-day festival — an ode to Top 40 music that shares a name with a popular radio app and is backed by the pre-eminent name in broadcasting — continues Saturday with performances by Lorde, Iggy Azalea, Ed Sheeran, One Direction and more.

Friday brought a steady dose of hits ranging from Coldplay’s classic “Clocks” and “Viva la Vida” to Nicki Minaj’s “Superbass.” Ariana Grande, the former Nickelodeon star whose music has dominated airwaves this summer, performed “Problem” and other hits in a cat-ear headband and thigh high stiletto boots.

There were a few surprises. will.i.am from the Black Eyed Peas came to back up DJ Steve Aoki, who worked in his signature gag by hurling a sheet cake at four volunteers in party dresses and button-downs.

Pete Wentz of Fall Out Boy crowd surfed from the comfort of a raft, and Jason DeRulo showed up to perform an unannounced set.

Performances got rowdier as the night went on. Motley Crue’s rendition of “Girls, Girls, Girls” was a frenzy of motorcycles, pyrotechnics and pole dancers. The Zac Brown Band, a country-folk group, covered Queen’s raucous “Bohemian Rhapsody.”

A more poignant moment came in a surprise appearance by Alicia Keys, who performed her new song, “We Are Here.” A rallying cry for peace, the song encourages listeners, “let’s talk about Gaza … let’s talk about Israel, cause right now it is real.”

Usher closed off the night by bringing a crowd-pleasing special guest on stage — Chris Brown, who performed his new single, “New Flame.” Their duet ended with a dance off before Usher slipped off his high tops and lit them on fire, letting them burn for a few moments before a stagehand put them out with a fire extinguisher.

iHeartRadio takes its name from the music app developed by the broadcasting giant formerly known as Clear Channel Communications. The company, which owns more than 850 radio stations, announced this week that it was changing its name to iHeartMedia to reflect the success of the iHeartRadio brand.