MashGet

They both ruled the '80s, redefined themselves in the '90s and, as this decade draws to a close, only one of the two biggest pop stars of this generation remains.

Madonna honored the late King of Pop Saturday night at the O2 Arena in London, the very same venue where Michael Jackson was scheduled to perform a 50-show run beginning later this month. Jackson's series of concerts were being billed as his farewell tour. Instead, MJ suddenly passed June 25 after suffering a cardiac arrest.