EXCLUSIVE

MLB Hall of Fame catcher Carlton Fisk was arrested for DUI last night in Illinois -- after allegedly driving his truck into the middle of a freakin' corn field ... law enforcement sources tell TMZ.

According to law enforcement sources, the New Lenox PD received a call about a car in the middle of a corn field around 7:20 PM.

When police arrived, officers say they found Fisk behind the wheel of his F-150 -- which had a flat tire -- and he appeared to be fast asleep. We're told cops also found an open vodka bottle in the vehicle.

Fisk was placed under arrest on the scene on suspicion of DUI -- and taken to a nearby hospital for a check-up. We're told he refused a blood alcohol test. His car was impounded.

Fisk was released this morning.