Adam Lambert was only 26 when he stepped onto the American Idol Season 8 finale stage alongside rock legends KISS — but what happened next became one of the most unforgettable performances in Idol history. Dressed in black with dramatic gothic wings, Lambert opened with an emotional rendition of KISS’ “Beth” before suddenly introducing the legendary band to a screaming crowd. Then Gene Simmons, Paul Stanley and Ace Frehley descended onto the stage in full KISS makeup and towering platform boots for “Detroit Rock City.”

26-year-old Adam Lambert had made it all the way to the American Idol live finale, when he was tasked with singing alongside one of the most legendary bands in the history of rock music.

Watch the shocking moment Adam Lambert upstaged rock's most legendary band  during all-star American Idol Final - The Music Man

This performance could have left the rising star broken beneath the pressure and sheer terror of having to stand out amongst the most recognizable act on the scene. But when Adam hit the stage, his vocals totally upstaged the pros.

Music Man readers can watch the shocking moment unfold in the video above – it’s already racked up more than 700,000 YouTube hits, with hundreds of viewers reckoning, “This is the most epic performance in Idol history!”

Musician Gene Simmons, finalist Adam Lambert, musicians Eric Singer, Paul Stanley, and Tommy Thayer of KISS perform onstage during the American Idol...

Adam hits the stage in a jet-black fit, a cage of gothic angel wings adorning his shoulders and his 2009 emo hair intact. His first verse instantly dazzles the crowd, who break out into screams and cheers, cutting through the heart-wrenching atmosphere of KISS’ megalithic ballad, “Beth.”

His vocals come steeped in emotion, confidence, and a magnetic sense of star power, as he enchants the audience with his tender melodies. But then, Adam shocks them all.

He exclaims, “Ladies and gentlemen – KISS!” leaving the Idol crowd to erupt once more in deafening applause. But the glam rock gods KISS couldn’t simply walk out on a stage during a live TV performance. They descend from a floating platform, hovering above the main stage as Gene Simmons, Paul Stanley, and Ace Frehley unleash their 1976 hit, “Detroit Rock City.”

Musician Gene Simmons, finalist Adam Lambert, and musician Paul Stanley of KISS perform onstage during the American Idol Season 8 Grand Finale held...

Painted in their full, iconic stage makeup, with six-inch heels and terrorizing black and silver costumes, KISS take to the American Idol finale as if it’s their very own arena show.

As KISS ditch their floating platform for the main stage microphones, Adam Lambert stands between the rock legends, seeming a little out of place as Paul Stanley belts out the hit’s first verse.

But as soon as Adam takes over the lead vocals, it’s clear he’s a fellow rock god in the making. His fearless voice and personality slot straight into KISS’ own aesthetic. When he reaches for some pitch-perfect high notes, he practically upstages the band on their own song!

The KISS medley evolves: “Rock and Roll All Night” blaring through the arena and transforming the Idol finale into an all-out party. After a few lines from Gene Simmons, Adam snatches the limelight again, singing with grit whilst weaving some show-stealing new vocal runs into the timeless hit. Even Paul Stanley smashing his glittering silver guitar on stage can’t distract from how epic Adam’s set-ending, glass-shattering high notes are.

Finalist Adam Lambert performs onstage during the American Idol Season 8 Grand Finale held at Nokia Theatre L.A. Live on May 20, 2009 in Los Angeles,...

Astoundingly, Adam Lambert lost out on the Season 8 American Idol crown. Arkansas singer Kris Allen beat the soon-to-be Queen frontman after more than 100 million votes were cast. But, to anyone who’s followed Adam’s career since, it’s clear who the real winner is; Adam’s KISS collab capturing every essence of what made him the legend he is today.