Renee Fleming must be very well-known for her capability in singing all kinds of arias from many Operas. But few people know this: she sings jazz songs too. Her wide range of musicality not only limited by her classical background, but turns out she can sing a song which is really different from what she's always doing.
Actually, Renee and Jazz is a long time friend. Before decided to take a classical music professionally, young Renee spent most of her time singing in a jazz band in a New York cafe.
This following video, Renee shows off her flawless vocal while singing the famous Duke Ellington's "In a Sentimental Mood", which is one of my favorites. Real diva!