The actor opened up to Rolling Stone about his decision to really sing and play the guitar himself while portraying the music legend in "A Complete Unknown" ... the drama chronicling the life of the renowned singer-songwriter.

It appears the "Call Me By Your Name" star was dedicated to accurately portraying Dylan ... obsessively studying the performer to the point he couldn't shake BD's speaking voice at times. However, it's Chalamet's singing voice that's drawn quite a bit of speculation ... with some wondering if he was really singing in the trailer released back in July.

As Chalamet told Rolling Stone, he played and sang all of Dylan's songs in their entirety for the film ... saying it was something he couldn't recreate in a studio.

He explained ... "If I was singing to a prerecorded guitar, then all of a sudden I could hear the lack of an arm movement in my voice."

Chalamet wouldn't be the first performer to be consumed with an impression. Austin Butler was famously roasted for failing to drop his Elvis Presley accent after portraying the King of Rock 'n' Roll in Baz Luhrmann's Oscar-nominated "Elvis" flick.

Chalamet has already moved on to his next big transformative role ... he's currently filming "Marty Supreme" -- a sports drama about a pro ping-pong player.

For the role, TC has ditched his iconic curly locks and grown a pencil-thin mustache ... making him nearly unrecognizable.