The "gleeks" were out in force Tuesday night.

The return of Fox's "Glee" drew it biggest audience yet with 13.7 million viewers singing along, The Los Angeles Times reports.

The show also posted a record 5.6 rating among adults ages 18 to 49, which is the highest rating in that demographic for any new show this season except the premiere of CBS' "Undercover Boss," which made its debut after the Super Bowl.

Each rating point in that demographic equals 1.3 million viewers.

Technically speaking, "Glee" actually premiered last May, but Fox calls that episode a "preview," not a premiere.

That premiere preview averaged 9.6 million viewers and also followed "American Idol."

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