The actors playing Big Poppa and B Rose have been training together in martial arts for over eight years. This made fight scene choreography much easier as they were well aware of each other's style, reach, and specialties.
In the beginning fight sequence at Albert Memorial Big Poppa caught B Rose in the nose with a powerful roundhouse kick. Assuming the nose might be broken and begin to swell they shot the rest of the fight sequence as fast as possible. The roundhouse kick to the nose made it into the final edit.