'The Crazy Ones' books Josh Groban as a guest star

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"The Crazy Ones" is adding another big voice to its guest star roster.

The new CBS sitcom has just booked singer Josh Groban for a guest star role, EW reports. He will appear the sixth episode.

Groban isn't the first singer to appear on the upcoming comedy. Guest starring as herself in the pilot is "American Idol" champ and chart-topper Kelly Clarkson. Though Groban won't be playing himself (as he did in an episode of "Glee"). He will play a "nerdy guy" whose crush on Sarah Michelle Gellar's Sydney is so intense he writes, produces, and performs a "creepy song about her."

"The Crazy Ones," starring Gellar and Robin Williams, premieres Sept. 26 at 9 p.m. ET on CBS.

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