Cher's "Believe" started life as a pop dance hit. With some help from American Idol's Associate Musical Director Michael Orland, Adam turned it into a heartwrenching ballad which became his most-talked-about performance in late 2018 - and his first true viral video hitting 3 million views in 3 days...
Yvonne Elliman's performance of the Bee Gees-penned "If I Can't Have You" is disco because in those days everything was disco. But the lyrics just don't make sense in that style - they are crying for a slow ballad to mean anything. Again, props to AI Associate Musical Director Michael Orland for enabling Adam to produce something new from something old.
As the author of the song Smokey Robinson says in the opening of the American Idol video, everybody always sings this song faster and with crescendos. Even Adam recorded the official studio version in the original style with a band and the Motown vibe. It appears that he came up with the acoustic arrangement in the last minute, and Simon called him "A Star".
For his American Idol performance of Led Zeppelin's "Whole Lotta Love", Adam kept close to the original. However, on the way to the Fantasy Springs concert on February 27, 2010, he came up with a slowed down arrangement which his band had no time to practice and pretty much improvised during the concert. Most Glamberts consider this a legendary performance.
It is well-known that Adam borrowed the idea for the Middle Eastern re-arrangement of "Ring Of File" from Dilana. However he further improved on the idea, and the result was magical, even if somewhat polarizing.
Again, Adam found an inspiration from another artist - in this case Gary Jules - and turned the song "Mad World" by Tears For Fears into a signature performance. It is still featured in many Adam Lambert concerts.