Sia was actually sick that day but didn't want to disappoint her fans, so she performed. Before her performance, she even said in the GMA interview that she cried in the dressing room because she knew she wouldn't hit the notes and was afraid that her fans wouldn't like her anymore
1 - About Mariah it actually was bronquites, it was a massive cold day (it was December at new york). She was at her 25th year career with nodules. I thought she still ate 2 - About Nicki yes, she sings. She actually has a good song where she's only singing which is called "Grand Piano" from her Pinkprint album. She performed the song on her tour in 2015 and she sounded amazing.
