Shia LaBeouf is so serious about his MC skillz, he's now ripping a DJ who put him on blast, and actual pro rapper Lil Yachty.
Shia turned in a new 3-minute freestyle Friday for Charlamagne Tha God to air on "The Breakfast Club" -- and it's straight fire ... for a guy who doesn't do this for a living.
The actor-by-trade was responding to a diss from Hot 97's Rosenberg ... who mocked Shia for freestyling on "Sway in the Morning" last month.
Take a listen, there's even a shot at Drake. Shia might want to consult with Meek Mill.