Paul McCartney provided the rough-hewn acoustic backing for an emotional Grammy night performance tonight by Rihanna and Kanye West. McCartney later added backing vocals for this first-ever performance of their new song ‘FourFiveSeconds,’ which ended with the entire Staples Center audience clapping along.

'FourFiveSeconds,' which was released last week as the lead single from Rihanna's forthcoming album, follows a separate studio collaboration with Kanye West -- giving a whole new generation the opportunity to learn more about this Beatles legend. That earlier song, called ‘Only One,’ featured West in an imagined conversation with his late mother.

While McCartney wasn't nominated tonight, Paul Epworth -- who worked on McCartney's most recent studio effort, 'New' -- was in the running for Producer of the Year, Non-Classical. The award went to Taylor Swift producer Max Martin.

Former McCartney bandmate George Harrison was recognized during the broadcast, and former producer Jeff Lynne performed a pair of favorites from Electric Light Orchestra.

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