Rihanna was left with "horrific" injuries after allegedly being assaulted by Chris Brown. The "Umbrella" singer was left with facial injuries following an argument on Sunday in which her boyfriend reportedly punched her in the face, causing swelling to her forehead and a split lip, as well as biting her on the arm.Rihanna refused treatment at the scene of the accident - which Chris fled from - but police took pictures which have been described as "devastating proof of abuse."A source said: "She looked like a martial arts fighter. Her injuries were bad."It is now believed it was not Rihanna who called police, but a passer-by who heard shouting coming from 19-year-old Chris' car.The altercation happened after the pair were seen arguing at a pre-Grammy awards party in California on Saturday.A source said: "Inside the party they were very lovey-dovey, but later on they were arguing.""Rihanna is now doing a lot of soul searching over whether their relationship can last. Only time will tell."The couple were also seen having a "scary" fight on Friday.A witness said: "I saw Chris Brown and Rihanna fighting at the Verizon party at Boulevard 3 nightclub on Friday night.""They were in this room and they were just screaming at each other, totally cussing each other out. They were screaming 'F**k you!' 'No, f**k you!' at each other, back and forth. They were right in each other's face. It was scary."Chris has hired Mark Geragos, who defended convicted murderer Scott Peterson and later Michael Jackson during his child molestation trial.He is due to appear in court on March 5 to answer charges of making criminal threats and police said he remained under investigation for charges of domestic violence after being released on $50,000 bail on Sunday.As a result of his alleged actions, the "Run It" singer has seen his adverts for Wrigley's chewing gum suspended.A company spokesperson said: "We believe Mr. Brown should be afforded the same due process as any citizen.""However, we have made the decision to suspend the current advertising featuring Brown and any related marketing communications until the matter is resolved."He has also pulled out of his commitments with the NBA All-Stars basketball team.