Is it true that Michael wanted to collaborate with Lady GaGa?

I have heard before that she was going to appear onstage with him at one of his "This is it" shows but I'm not sure if it's true or not

Yep it's true but unfortunately he couldn't do that

i hope it's not true,i have heard about it but to be honest...don't hate me but i wouldn't find a good idea to Lady Gaga open his shows,i don't like her at all,either as a singer or a person
Beyonce would be better