Taylor dropped her first single off her upcoming "Reputation" album Thursday night and called out Kanye in the opening verse, where she sings "I don't like your little games ... don't like your tilted stage."

Our sources tell us the song is definitely targeting the Wests, who Taylor feels betrayed her by releasing their now infamous phone convo. Taylor's side of the story has always been ... they discussed the lyric but she never approved Kanye calling her "bitch" in "Famous."

We're told Taylor feels she was backstabbed by the couple and there will be more not-so-subtle hints in the official music video, which will debut Sunday during the VMAs.

Taylor released a short clip that zooms in on her sitting on a throne ... with the inscription, "et tu, brute."

When the disses turn Shakespearean ... you know it's serious.

It's a famous line from Shakespeare's play "Julius Caesar" when Caesar is being stabbed to death and recognizes one of his pals, Brutus, is in on it. The phrase is now meant to symbolize backstabbing.