Reports: Rihanna Victim in Alleged Brown Attack

"Extra" has uncovered more information about Chris Brown's arrest on battery charges yesterday.

The R&B singer posted $50K bail and was released from custody yesterday at approximately 6:30 PM -- after his SUV was chased through L.A. streets. Brown, who was booked on charges of making felony criminal threats, faces up to 9 years in prison.

New reports today confirm that Brown's superstar girlfriend, Rihanna, was the victim of the alleged attack -- and suffered bruises, scratches and even a bite mark (some reports have said she has a broken jaw), but her people are not commenting except to say "she is well."

This morning, Rihanna's father told Splash News that his daughter told him she was in a car wreck. "She told him the reason she was pulling out of the Grammys was because of a shoulder injury," Sam from Splash News dishes to "Extra."

On Friday, the couple looked cozy at Timbaland's Pre-Grammy party where Rihanna performed for the star-studded crowd. The singing duo also appeared at Clive Davis' Pre-Grammy party on Saturday.

Rihanna and Chris inexplicably left the bash at 12:20 AM in the middle of P. Diddy's performance -- and were snapped in Brown's rented Lamborghini, which "Extra" has learned rents for $2K a day. Ten minutes later, LAPD received a 911 call about a domestic violence incident in Hancock Park.

Both Rihanna and Brown canceled their Grammy performances on Sunday afternoon -- giving Justin Timberlake and Al Green the opportunity for an impromptu Grammy performance. News of the alleged incident stunned attendees, including actor Blair Underwood, who said, "That's unfortunate -- that's very unfortunate."

Now, "Extra" has uncovered evidence of abuse in Brown's past -- with his stepfather allegedly abusing his mother. "In the cover story for Giant magazine, Chris Brown talks about telling his mom that because his stepfather was so abusive to her that one day he would go to his stepfather's job and beat him with a baseball bat," Emil Wilbekin of Giant magazine dishes to "Extra."