According to MediaTakeOut.com, the 24-year-old singer stumbled and fell into a grate, slicing open her leg, the New York Post reported.
Her attacker yelled something about her rapper boyfriend before hurling the bottle of soft drink Lucozade at the star.
Chris Brown infamously beat up Rihanna in 2009, and fans have never forgiven him.
Apparently some of that anger has spilled over to Rihanna, after her decision to get back together with the hothead last month.
Chris Brown and Rihanna raised eyebrows at last Sunday’s Grammys when they smiled and snuggled throughout the ceremony, four years and a day after he sent her to the hospital on Feb. 8, 2009