In the key of fake

Teen songbird Ashlee Simpson had a microphone malfunction on " Saturday Night Live" last night, scurrying off stage when a production glitch caught her lip-synching the wrong tune.

The pop star, younger sister of singer and TV star Jessica Simpson, sounded great belting out " Pieces of Me" in her first segment on the show. It was the same song that she butchered at August' s MTV Music Video Awards, drawing withering reviews for a flat, out of key performance.

But the triumphant moment turned into a debacle when she came out to debut the song " Autobiography" for a second set. But whoever was responsible for piping in a studio-engineered rendition for Simpson to mouth screwed up, playing " Pieces" once again.

The raven-haired beauty hopped around briefly, then slinked off the stage as her hapless band half-heartedly faked away. It didn' t take long for critics to vent their rage on Ashlee Simpson' s official Web site.

" Finally, you' re exposed for the fraud that you are," wrote an E-mail poster named drdrewby minutes after the embarrassing performance. " You have cheated your fans and people who actually thought that you had a lick of talent. You should quit the music business because you are now and always will be a complete and utter joke."

Said CowboyJeff99: " I knew she sounded like crap live, so I was ' wondering' what was going on when her voice sounded just like the radio edit."

When the cast of the live show came out to bid the audience good night, actor Jude Law tried to explain Simpson' s slipup.

" What can I say folks, live TV," Law shrugged.

A still-humiliated Simpson apologized to her fans - and blamed her band for playing the wrong song.