Both TMZ and the New York Daily News are now reporting that Rihanna was the victim last night of boyfriend and fellow R&B wunderkind Chris Brown's assault. The couple reportedly fought in a car after Clive Davis's pre-Grammy party, and a security guard at Cedars-Sinai Medical Center tells the Daily News that Rihanna was treated there last night. Brown, 19, is out on $50,000 bail after turning himself into the LAPD. Brown was not originally booked on suspicion of having physically hurt his victim, but "there may be domestic violence charges added later, but that will be up to the district attorney's office," a police sergeant told the Associated Press. Both Brown and Rihanna cancelled their scheduled appearances at the Grammys last night.