updated 02/20/2012 AT 11:00 AM ET
•originally published 02/20/2012 AT 2:05 PM ET
Likely to spark even more controversy than Brown, who pled guilty to assaulting Rihanna in 2009, appearing at the Grammys is rumors that he was at her early birthday bash last week and is singing on a remix of her track “Birthday Cake,” called “Cake.”
Brown meanwhile is celebrating his recent Grammy win in South Beach. He took over the deejay booth Saturday night at Cameo with friend Tyga and partygoers enjoyed a life-size cake in the shape of a Grammy.
“Chris performed three of his hottest hits, including Look at Me Now, Another Round and Strip,” a source tells PEOPLE. “The fans went wild and he stayed at Cameo till 4:30 am.”
With reporting by LINDA MARX