When you first see Britney Spears, she'll be a nerd, but just wait — as her episode of "How I Met Your Mother" goes on, she'll gradually become more like the sex symbol we used to know and love. At least, as much as a dermatologist's receptionist can be.

In the episode, called "Ten Sessions," Ted Mosby (Josh Radnor) wants to get an embarrassing butterfly tattoo removed, and he wants to see if his dermatologist, Dr. Stella Zinman (played by "Scrubs" star Sarah Chalke), will fall for him in the process &8212 but he hooks Spears' character Abby instead, without realizing it. Abby starts off being mousy, wearing glasses and cardigans, but she transforms herself to win over Ted.

"She has a total spazzy crush on Ted," show co-creator Craig Thomas told TV Guide.

As Ted's sessions continue, so do Abby's attempts to get his attention with sexier hairdos and clothing, and frequent nervous laughter. In a video clip from the episode, Ted asks to see the doctor.

"I'll let her know," Abby responds but continues to stare longingly at him, without picking up the phone.

"Telepathically?" he asks.

"That's funny!" she laughs awkwardly. "Ha! That's funny, smart and great!"

By his next appointment, Abby is reading the book, "The Power of Me," that he had brought with him during his last session. She notices he's starting to grow a mustache, and comments, "Love the 'stache! You look like a young Tom Selleck, only a million times handsomer." Without taking her eyes off him, she calls her boss and says, "Dr. Zinman, Magnum's here to see you." After a beat, she tells Ted, "Just kidding."

"[Spears] was so funny, and she already had her character down pat," Alyson Hannigan, who plays Lily on the show, told TV Guide. "I had no idea she had such great comic timing."

Perhaps the pop star hasn't forgotten what she learned mixing sketch comedy with song and dance on "The Mickey Mouse Club." Jason Segel, who plays Marshall on the show, told TV Guide that Spears contributed to the episode's dialogue with a few improvised lines that were "really good."

"She came up with stuff that had everyone laughing," Segel said. "She's definitely a comedian."

So, with such approval from the cast, could Spears be back for another appearance? After all, the promo for the episode shows her in a conversation with Barney (Neil Patrick Harris), which seems to reveal that she might have moved on to Ted's friend, since she asks him, "Can we have sex and then go shopping?"

"The episode ends on a funny note that I won't give away," Thomas said. "But it definitely leaves it open for her to come back."