Dwight Gooden's got a real-deal boxing match coming up, and he clearly ain't taking his opponent lightly ... 'cause the MLB legend hit up the UFC Performance Institute in Vegas for a hardcore training sesh.
The 54-year-old NY Mets legend is facing 29-year-old "Nitro Comedy Tour" star Catfish Cooley -- who's gone viral on YouTube for his redneck comedy -- on March 7 at the Showboat Casino in Atlantic City.
Gooden -- a 4x All-Star and 3x World Series Champ -- recently hit up the PI ... and worked on his striking with his coaches.