Kanye West isn't the only one having pre-performance meltdowns this week. According to TMZ, Rihanna bailed on her Grammy performance due to a meltdown during her rehearsal, and not due to bronchitis, as had been previously reported.

Rihanna was reportedly "loudly expressing displeasure" during her Grammy rehearsal Monday afternoon and left shortly thereafter. Sources told TMZ that she sang well during the rehearsal. Her performance two days earlier at the Lionel Richie tribute was stunning. She did not offer an explanation on her Grammy absence in her Twitter apology to her fans.

The plot thickens. Watch an excerpt from Rihanna's Lionel Richie tribute performance below.