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Lisa Kudrow showed up in the spotlight as her "Friends" character Phoebe Buffay and sang her famous song "Smelly Cat," even giving the Grammy award-winning singer/songwriter Swift some tips on singing the song with feeling.

Kudrow wasn't the only star to join Swift recently at the Staples Center in Los Angeles. Justin Timberlake, Serena Williams, Lorde and Ellen DeGeneres have sung with the superstar, Time reported.