A missing piece in the fight between singers Rihanna and Chris Brown has been revealed. TMZ.com is reporting that the woman who sent a three-page text message to Brown was his manager, 39-year-old Tina Davis. The text message is believed to have sparked the argument on the eve of the Grammy Awards that caused Brown to allegedly beat up his girlfriend, threaten to kill her, and leave her on the side of the road in L.A. "Law enforcement tells us the text message to Brown talked about hooking up later--and it totally pissed off Rihanna. She slapped and hit him and he then brutally fired back," TMZ reports. "The detective's affidavit refers to the text message as being 'from a woman who Brown had a previous sexual relationship with.'" Brown has been charged with two felony counts but the couple have reconciled.