What song did USHER sing at the 2010 grammy's with jimmie fox who were introduced by robert downy jr.?

Well, Jamie Foxx sang Blame It with T-Pain and then Usher sang Earth Song with 4 other artists. Earth Song is a Michael Jackson song and Blame it(on the alcohol) is a song that Jamie Foxx sings, featuring T-Pain. But I don't recall them singing together. Hope this helps!