Adrian Peterson was heavily intoxicated at the time of his arrest, which was very out of character for the NFL star ... this according to the club where he was busted early this morning.

Daniel Maher, general manager of Live at Bayou Place, tells TMZ that Peterson has been to the club before, but he has never known him to drink much. Last night, however, Maher said Peterson was ver drunk and was a difficult customer all night.

Maher says Peterson was throwing his ego around and making people mad, so they put him in the VIP area. Maher says when the club was closing, he rushed over to the bar to try and order one last drink and when he wouldn't Maher says Peterson "tried to intimidate the bartender" into selling it to him.

According to Maher, that's when he intervened, but Peterson continued to be "unreasonable." That's when Maher says the off-duty cop intervened, and, as TMZ first reported, Peterson proceeded to shove him.

Maher says during his confrontation with the officer, Peterson assumed a fight stance and looked "like he meant business." Maher says, "He looked really scary and I thought he was gonna attack the cops."

Maher says that once the officers subdued Peterson, the NFL star apologized for his behavior and told cops he doesn't usually drink.

Peterson was eventually booked into jail and charged with resisting arrest.