Britney Spears could make third appearance on 'How I Met Your Mother'

Britney Spears could make a third appearance on CBS sitcom How I Met Your Mother, the show's creator, Craig Thomas, has said.

Thomas said that Spears' second appearance, due to air Monday, was written to leave the door open for the 'Toxic' singer to make a return appearance next season.

He tells THR.com: "She was better than the first time and I think the fans will enjoy it because her return answers a larger mystery set up earlier in the series.

"So there's a good plot reason why she's there. And when people watch Britney's second appearance on the show they'll see that the door is still open for her to come back."

Spears, 26, has been the most high-profile celebrity guest to visit the set, following past appearances by Mandy Moore, Enrique Iglesias and Heidi Klum.

Her cameo as a bubbly, sweet, receptionist created so much buzz that 10.6 million viewers tuned into watch her first episode on March 24 -- making it the most-watched episode of the series ever.