Justin Timberlake, who had been scheduled to perform this evening on NBC’s Tonight Show, has cancelled his performance. A source with knowledge of the situation says Timberlake will still sit down to chat with host Jay Leno, but is no longer going to perform, because he is “under the weather.” Earlier in the day, another source said tonight’s Timberlake performance may have been scrubbed to ensure maximum impact tomorrow night, when the pop star is scheduled to perform a free concert on Hollywood Blvd. compliments of ABC’s competing late-night show Jimmy Kimmel Live.

Kimmel, looking to make noise in the walk-up to Jimmy Fallon’s takeover of Tonight, announced earlier this month his show would shut down Hollywood Boulevard tonight — the first day of the official 2013-14  broadcast TV season –  when Paul McCartney makes his first appearance on the show and performs on the street.  At that time, Kimmel announced he’d close Hollywood Blvd. again, tomorrow night, so Justin Timberlake could perform  songs from his new album, The 20/20 Experience, which hits stores September 30, and chat with Kimmel about his role in his new movie.

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