Janet Jackson to Open VMAs With Tribute to Michael

Ms. Jackson is set to put on a huge MJ-honoring performance featuring 20 backup dancers -- which is being put together by some of the best choreographers in the world, including Frank Gatson and Travis Payne.

According to Kryiss Grant, one of the dancers involved (who was also an usher at MJ's burial), some rehearsals have lasted 15 hours a day. Once Janet is finished honoring her brother, Grant tells us "there won't be a dry eye in the house."