Details are still sketchy, but according to online reports, singer Chris Brown hauled off and punched singer Rihanna in the face during a heated argument in their limo after they left the Clive Davis Pre-Grammy party in LA.

x17online.com reports that Brown turned himself in to police Sunday evening and was released on $50,000 bond about 90 minutes later. He was accompanied by his attorney Mark Geragos.

Last week rumors swirled that Chris was cheating on Rihanna with another woman — Trey Songz’s ex-fiancee, who Chris recently hired as one of his dancers.

The former lovebirds strived to give the appearance of still being a loving couple at Clive’s party, but as you can see by Brown’s body language above — he was already over the relationship.

An inside source informed us that the trouble started when Chris considered Rihanna to be “damaged goods” after he discovered she had contracted Herpes. [LINK]

There are also rumors circulating that Rihanna contracted Herpes from another popular rapper who performed during the Grammys telecast Sunday night. They say Brown was acutely aware that Rihanna was getting her back blown out often and repeatedly by this married rapper.

The LAPD say a warrant was issued for Brown’s arrest after an “unidentified” female filed domestic assault and battery charges against him following that early morning brawl. But sources say the woman, who sustained “visible injuries” on her face during the attack, was Rihanna.

This story exploded all over the Internets on Sunday just hours before Chris and Rihanna were scheduled to perform during the Grammy Awards telecast.

Grammy reps announced both artists canceled their appearances by late Sunday afternoon, and that’s when rumors began swirling wildly.

Rihanna and Brown began dating in 2007 soon after the story broke of the scandalous relationship between the teenager and his 30-something manager. It all seemed so convenient at the time.

Once Rihanna found out that Chris was cheating on her, she should have packed her things and bounced right then. But instead, she made the same innocent mistake that many young women make by sticking around and hoping their man will get over his cheating ways.

Photo: Getty Image