"Glee" drew 13.3 million viewers and a 5.8 preliminary adults 18-49 rating -- dominating the night, rising 4% from its mammoth premiere last week and scoring the Fox pop-drama's biggest rating ever (yes, higher than the show's Madonna-themed episode).
Among those millions of viewers was Spears herself, who posted her thoughts on the episode in real time on Twitter, as "Glee" aired on the West coast. "Watching 'Baby' brings back so many memories! Feels like yesterday," Spears tweeted, later adding, "The 'Glee' version of 'Toxic' is amazing!"
"I loved it!" Spears wrote at the show's conclusion. "Thank you guys SO much for making this happen!"
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Additional reporting by Monica Herrera, Billboard.com