The singer has been battling flu-like symptoms and laryngitis, and was forced to cancel a charity concert on Thursday night.
“Bronchitis and laryngitis boo! I’m still goin to rehearsals tho! Sunday is everything,” she tweeted on Friday.
“Rihanna will perform with Eminem, as scheduled,” a friend of the singer told Radar Online. “Rihanna is on steroids and antibiotics to get her as prime time ready as possible for Sunday night.”
The singer is nominated for four songs and the duet she is scheduled to perform with Eminem, Love the Way You Lie, has been nominated for Record Of The Year.