Rihanna had to cancel herGrammy performance after it was alleged that she and her boyfriend Chris Browngot into a fight.

When the police came on the scene Chris Brown was nowhere in sight - he however turned himself in at the Wilshire station but was later released from jail after posting US$50,000bail. Chris Brown was booked on suspicion of making criminal threats.

According to E! News a source admits that the alleged victim was Rihanna, 20, and that she suffered visible bruises on her face during an altercation that took place hours earlier. Both in turn balked on scheduled Grammy performances.

A spokeswoman for Brown's label declined comment. Rihanna's publicist, Amanda Silverman, would only tell E! News that the 20-year-old "Disturbia" singer was involved in an unspecified traffic mishap. "Rihanna is well," the rep said. "Thank you for concern and support."

Per department policy, police declined to identify the alleged victim in the incident, which occurred about 12:30 a.m. in the Hanc**k Park area, apparently as the two were heading home from Clive Davis' annual pre-Grammy bash, where they had been all smiles.

In a statement, police say Brown and his companion "became involved in an argument. After stopping his car, Brown and the woman got out and the argument escalated. The woman suffered visible injuries and identified Brown as her attacker."