Chris Brown Sues Basket Ball Player For Extortion

Chris Brown is in an unusual position in court -- on the OFFENSIVE -- claiming a guy on a basketball court tried extorting the singer ... threatening to tell cops Brown started a fight unless he coughed up a ton of money.Brown was sued by Malcolm Ausbon over a pick-up basketball game last July at an L.A. gym.  Ausbon claims Brown attacked him over a foul call, and proclaimed he was a member of the Bloods.

Brown has now counter-sued Ausbon, claiming he had nothing to do with the fight and Ausbon knew it, but tried to shake him down for a quarter-of-a-million dollars.  According to Brown's new counter-suit -- obtained by TMZ -- Ausbon admitted to Brown's people the singer was not the culprit, but later his lawyer made this written demand:

 -- "Mr. Ausbon believes $250,000 will suffice compensating him for his physical and emotional injuries ... Mr. Ausbon is placed in a position by the LAPD where he needs to decide whether he will press charges for aggravated assault and battery."

The letter continues:

-- "However, Mr. Ausbon prefers not to resort to filing these claims or the lawsuit.  He would rather be compensated."

Brown's lawyer, Mark Geragos, says in the counter-suit Ausbon promised to keep the matter secret if Brown anted up.  Brown didn't pay and Ausbon filed his lawsuit.