Alicia Silverstone has reportedly pulled out of How I Met Your Mother after learning that Britney Spears had bagged a guest spot on the quirky U.S. TV sitcom.

The proper actress was set to star alongside Britney, after the singer's agent agreed a deal with producers - with her father’s approval.

However, Pink Is The New Blog is now reporting that Alicia has pulled out of the show because she feared being "overshadowed" by the pop wreck's presense.

A source told TMZ yesterday that Britney's foray into TV was "a small legitimate project that will keep her busy doing something."