The performance, this recording of the Roosevelt and Garfield school bands, didn’t quite sound right here. Tinny. Screeching. Meant for louder speakers, wider audience. But as the beats reached their crescendo, pausing and then transitioning triumphantly into the electric guitar of “I Gotta Feeling,” Black Eyed Peas member Jaime Gomez gave frontman William Adams’ manager Childress a double high-five.

“Woo!” Gomez, better known as Taboo, yelled.

It was the “icing on the cake,” as band founder Adams described it, of the Black Eyed Peas’ halftime show at the East L.A. Classic on Friday — a joint rendition of “I Gotta Feeling” alongside the Roosevelt and Garfield bands. After the teams exited the field at halftime of an eventual Garfield 16-8 win at the Coliseum, the Black Eyed Peas took to the peristyle for a halftime show that shined a wide strobe on East Los Angeles. Garfield’s Damian Cabrera scored his second touchdown of the night in the fourth quarter to break an 8-8 tie.

Lights flashed across the timeless arches, the group performing “Let’s Get It Started” and “Boom Boom Pow” under the tall orange flame of the lighted Coliseum torch.

And at the end of the performance, the recording on Childress’ phone took to life as a backing track, the school bands and cheerleaders and color squads assembling alongside the Black Eyed Peas on USC’s home turf for a bass-pounding rendition of “I Gotta Feeling.”

“We are familia!” Adams, who grew up in Boyle Heights, yelled to overwhelming cheers as he left the field. “Fa-mi-lia!”

It was an explosion of hometown pride, “East L.A.” chants ringing across the field in the most blowout event in the Classic’s near centuries-long history — the Black Eyed Peas, the 28,000 in attendance elevating the Classic’s longtime vibrancy to never-before-seen heights.

“This is something special,” Roosevelt senior captain Alexander Arroyo said at the Classic’s media day Wednesday. “I never thought I’d ever be here.”

It seemed a difficult endeavor to stay composed amid the hype, but Roosevelt keyed in on a defensive game plan to shut down Garfield’s passing game from the opening snap. “They’re going to bring the house,” Garfield coach Lorenzo Hernandez said pregame, “and the footing from the house.”

Their defensive front stifled the Bulldogs in the first half, Arroyo picking off a pass on Garfield’s first drive of the game and the Bulldogs coughing up the ball on their second. Roosevelt, meanwhile, handed the ball to senior Isaiah Wright on a fourth and one on their first drive of the game and watched him burst down the left sideline for a rollicking 51-yard touchdown run.

Their double-wing offense, executed to near-perfection this season in an 8-0 start, flourished early as three Roosevelt backs gained more than 35 yards in the first half.

“We have too many threats for them to stop,” senior Jared Andrade said. “You stop one of us, you still got five more coming at you.”

Held for years at East L.A. College, Roosevelt senior Andrade said he expected the community support for Friday to be larger despite the move to the Coliseum.

Indeed, Coliseum president George Pla announced Wednesday they had already sold 27,000 tickets — estimating proceeds of about $500,000 that would be split between Roosevelt and Garfield’s athletic budgets. And the venue brought a rarefied air to an already-intense matchup with playoff implications, as both teams entered undefeated in the Eastern League.

For a moment Wednesday, Roosevelt players hung over a balcony on the Coliseum’s peristyle, taking a moment to soak in the quiet of a historic venue before the storm Friday night.

Roosevelt running back Isiah Wright breaks away from the Garfield defense to score a touchdown in the first half Friday.

(Wally Skalij / Los Angeles Times)

Roosevelt junior Naszeer Reed and senior Johan Alfaro have grown up in the Estrada Courts public housing project — same as will.i.am — in Boyle Heights, Reed said. It’s a hard life, the junior added, his mother working “three to four jobs,” as he said, to try to provide. He joined the Boys and Girls Club of Estrada Courts to stay away from gangs.

The organization was bringing a few kids to the Classic, Reed said Wednesday. And playing at USC’s home field, playing on the turf of legends, was motivation — for him, for them, for an entire East Los Angeles community.

“I’m happy that I get to inspire, me and Johan get to inspire, Roosevelt … some of those kids in the projects to come and play football,” Reed said.