Could Michael Jackson Have Performed Awaited Comeback Concerts?

Sources close to Michael Jackson said Friday that the "King of Pop" wouldn't have been physically capable of doing the 50 concerts he was scheduled to begin this summer, reports FoxNews.com.

According to these sources, Jackson, who died Thursday of a heart attack, originally signed on for five shows, but the company promoting his comeback concerts, AEG Live, kept adding more.

All 50 shows sold out in minutes, according to Fox News.

Jackson had been rehearsing eight hours per day, but was sporadically seen arriving to rehearsals in a wheelchair. Those close to him say that the pressure of the 50-concert run in London got to the innovative superstar, adding to his declining health. During the rehearsal period, his prescription drug intake would reach dangerous heights.

His health in recent months led many around Jackson to doubt whether he would perform at all; while John Kohan, a friend of Jackson, said he was excited for the upcoming concerts and in good health.

Allgood Entertainment reportedly signed a contract with the late pop star to join other family members in a reunion concert. The document states that Jackson wouldn't perform anywhere before the concert scheduled for this summer or three months after it. As a result of Jackson's deal to play 50 shows in London with AEG Live, Allgood Entertainment filed a lawsuit earlier this month for $40 million dollars in a Manhattan federal court claiming he breached their agreement.

Jackson was paid a $40 million advance for his concert series in London. According to Billboard, he would have made upwards of $400 million in the three-year tour.