In recent years, the "king of pop" has bailed out on a comeback tour with his brothers who made up The Jackson Five and an album for which Sheikh Abdulla of Bahrain paid $7 million but never received. Abdulla sued and the pair settled out of court.
Jackson's last performance, at the 2006 World Music Awards in London, when he sang just a few lines of the song "We Are the World," was a disappointment. It was his first appearance since his 2005 child molestation trial, in which he was acquitted.
Then there's the matter of Jackson's health. Recent pictures have shown him being pushed in a wheelchair, appearing frail and gaunt and wearing a "Zorro" mask while being helped across the street. In December, there were reports that Jackson was on his deathbed suffering from a rare lung condition, which his publicist denied.
"I find it astonishing that he's physically able to do it," said Brown, who co-wrote the Jackson biography, "Michael Jackson: the Man behind the Mask." "Michael will be 51 this year. This is not 'Benjamin Button.' He is not growing younger."
Brown recalled seeing Jackson's last live concert performance at Madison Square Garden in 2001 for his 30th anniversary show. Jackson buried his head in brother Jermaine's chest. Later, Brown talked to Jackson's brothers about it.
"Most people thought it was part of the show, but Michael was exhausted," he said.
"Michael Jackson was more famous for being a performer than being a singer," Levine said. "He's going to have to play his hits, dance the way he danced, be the person he was when he was popular. I'm not sure he's in that kind of shape."
Whether he'll moonwalk across the stage remains to be seen, but concert organizers have at least been reassured that Jackson is fit to perform.
"The man is very sane, the man is very focused, the man is very healthy," Tim Leiweke, the president and CEO of AEG, the entertainment company putting on the tour, said yesterday at a symposium sponsored by Billboard. "I think he has been dragged through the mud."
"Despite everything you read about him, he was fine," added Leiweke. "The man took a physical for us to go do these concerts."
Brown said Jackson is producing a "Thriller" show, in which he'll perform the music from his most successful album, "Thriller," which remains the best-selling album of all time.
The tour should also boost Jackson's bottom line.
"I recall Michael himself saying he didn't want to perform anymore. He's in that proverbial rock-and-hard-place situation," said Brown, who believes he's doing the tour for the money. "How else is he going to make money?"
There have been reports of financial trouble ever since his 2005 child molestation trial. Last year, he was forced to sell his famous Neverland ranch.
In April, 2,000 items from his Neverland estate will be up for auction at the Beverly Hills Hilton. The entire sale is estimated to bring in between $1.5 million and $3 million, according to Darren Julien, the head of Julien's Auctions, which is conducting the sale.
"I don't get into his personal finances," Julien told ABCNews.com. "It's not something I know much about, but I do know the best way to look at it is he's ending one chapter of his life and going on to the next chapter. That's going to be bigger and better."