Glee brought in a series high 13.3 million viewers on Tuesday night, thanks to Britney Spears' guest appearance on the hit Fox show, according to Billboard.

The episode was filled with Spears' hits, with Heather Morris (who plays Brittany) doing most of the singing. Morris donned Spears' iconic red catsuit from "Oops … I Did It Again" as well as the python from Spears' VMA performance of "I'm A Slave 4 U." Lea Michele performed a version of "…Baby One More Time," while Spears herself joined Morris and Naya Rivera (who plays Santana) to sing "Me Against the Music."

John Stamos also appeared in the episode as Brittany's dentist/Ms. Pillsbury's new love interest.–ISHITA SINGH

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