Chris Brown is doing what he does best -- fighting back ... in this case using legal means by filing a countersuit over the Frank Ocean brawl in West Hollywood.
You'll recall ... Chris and Frank got into it outside a recording studio back in January. The building was damaged and Sha'Keir Duarte -- Frank's cousin -- claimed he was kicked and beaten by one of Brown's bodyguards. Duarte sued Chris in August for his injuries.
Now Chris has fired back, claiming Duarte provoked the fight by threatening to kill him. In the countersuit -- obtained by TMZ -- Chris claims Duarte kicked and punched him.
And get this ... Chris -- who is currently in rehab for anger management and faces criminal assault charges in D.C. -- claims he attempted to avoid the confrontation "with the aggressive and hostile Mr. Duarte."
Chris says this is a shakedown for $$$, saying Duarte's demand for $2 million is absurd.