Britney Spears relaunches her career as a clean-cut nerdy girl in TV comedy

Here is Britney Spears relaunching her troubled career - as a clean-cut nerdy girl in a TV comedy.

The pop superstar is trying to shake off her reputation as the world's most high-profile train-wreck with a guest spot in U.S show 'How I Met Your Mother'.

And fans will be stunned to see the singer as a nerdy receptionist coming across like a teenage girl with a crush on cute on Ted, played by Josh Radnor.

"She's in mousy clothes," says co-creator Craig Thomas. "She has glasses her hair is plain, and she has a total spazzy crush on Ted."

But by far the biggest shock comes from behind the scenes - with the show's creators and other actors all singing Britney's praises.

Perhaps most amazingly, she even turned-up EARLY for her first day at work - and managed to keep up the good time keeping and overall work-effort.

"She's friendly, shows up on time, knows all her lines, nails all of her jokes," said co-star Radnor. "The only thing scandalous about all of this is how non-scandalous it is."

Fellow co-star Neil Patrick Harris admits he was skeptical when he heard the star, whose last high-profile TV spot was her disastrous showing at the 2007 MTV Video Music Awards, was signing on to their show.

"I kept saying, 'You're serious? She's going to do it? She's not going to back out?'," he admits.

But he hoped the experience may be a good grounding one for Britney. "I don't know how often she's just hung out with other actors and normal, regular people. I hope she enjoys the system."

The show is far from one of the biggest headline-grabbers in the U.S., and so when the show's bosses heard Britney was gunning for a guest spot they also found it hard to believe.

"We thought it was a prank!" co-creator Thomas admits.

Within 24 hours of her agent saying she was interested - and a script rushed over to her - Spears had signed on.

"She wanted to work on her acting chops and play a specific comedic role," Thomas said.

Given her reputation, they were thrilled when she arrived early for the 10am first read-through of the script.

"She seemed nervous at first," Thomas said. "When she started getting laughs she started having a good time.

"We don't have a high-pressure environment. We don't shoot in front of a live audience so we can shoot as many takes as we want.

"I think that atmosphere really appealed to her and she felt comfortable."

The show's stars insist they were all impressed with the superstar singer's acting, especially her ability to make them laugh.

Jason Segel said: "Her improvs were really good.

"Sometimes at table reads you play around with lines and try different things.

"She came up with stuff that had everyone laughing.

"She's definitely a comedian."

Alyson Hannigan added: "She was so funny and she already had her character down pat.

"I had no idea she had such great comic timing."

Hannigan also felt the need to mother Britney during filming.

"I was checking on Britney all the time," she said. "And I felt very protective of her, and I wanted to make sure she was happy and comfortable."

Britney's spot on the prime-time show is booked as a one-off guest spot. But bosses have certainly not ruled out her return.

"The episode ends on a funny note - it definitely leaves it open for her to come back," Thomas said.

Britney seems open to the idea, too.

"I'm having a blast," she said. "Working at 'How I Met Your Mother' has been so terrific. Everyone has been wonderful."