John Mayer didn't sing at Michael Jackson's memorial because he isn't as talented as the late 'King of Pop'.

The 'Gravity' musician - who performed an instrumental version of Michael's hit 'Human Nature' at the ceremony at Los Angeles' Staples Center on Tuesday (07.07.09) - decided against tackling the vocals as he didn't want to be compared to Michael.

He said: "The decision not to sing cam from knowing what's best for me. I think it's a mine field to try in any way to replicate vocally what Michael Jackson has done. And in a way, it was sort of respectfully leaving an absence, you know, sort of the presence of his absence."

John, 31, was amazed to be asked to attend the memorial - which also saw performances from Mariah Carey, Usher and Michael's brother Jermaine Jackson - as he had never met the 'Billie Jean' singer.

He explained: "The first thing I said was a question, 'Does this really come from the family?' I think that was essential to me to be able to process the honor. It took me about 48 hours to strike the balance in how I was going to approach being invited to this unbelievable event without actually having the proximity to Michael Jackson, personally. I'd never met him."

Michael died of a suspected cardiac arrest last month aged 50.