When I watched Sir Paul McCartney on stage at the GRAMMYs performing with Kanye West and Rhianna I couldn’t help but wondering what in the world he was doing up there.

It was 51 years ago on Monday that the Beatles changed the world with an appearance on The Ed Sullivan Show.

How do you go from singing lead with the greatest band in the history of rock to backup singer and guitar player for Rhianna and Kanye West? Very well thank you.

You can listen to 'FourFiveSeconds' below.

Paul looked just like himself out there in a song that he easily could have sung on his own. I couldn’t help but wonder what he would have said in 1964 if someone told him he'd be sharing the stage with Kanye and Rhianna 51 years later.

It’s not the first time Paul has sung with other people. In fact in 1982, he sang with Stevie Wonder who will be honored by the GRAMMYs next Monday. At least in that song, he got to sing a verse. With Kanye and Rhianna, he only played guitar and sang harmonies.

There is a mutual benefit to the collaboration with West. Now, McCartney is able to get more mainstream exposure, and is exposed to an even younger generation. After all, it did work for Tony Bennett and Lady Gaga. I thought were great!