Thousands of hopefuls are going to show up tomorrow at a hotel in downtown Manhattan to try out for American Idol 2 -- where they might find a huge surprise.

Sources say Idol is adding a fourth judge to its panel: Hot 97 radio personality and singer Angie Martinez.

She is said to be in negotiations to join Simon "Mr. Nasty" Cowell, producer Randy Jackson and '80s icon Paula Abdul when the blockbuster talent show comes back early next year.

Because auditions are taped and become a big part of the show -- some say the funniest part -- lines had already started to form yesterday outside the Regent Wall Street Hotel, two days before the doors open.

Thousands of singers are expected to try-out for a shot at stardom. So we asked a music industry professional for advice to first-timers about getting past the first round.

"I would try and find a song with commercial appeal that also allows you to demonstrate your vocal range, your ability to sustain notes and show that you have a sense of rhythm, something that shows off your best assets" says Virgin Records' senior vice president Steve Leeds.

Forget trying to butter up the judges, Leeds says. Act as naturally as you can -- given the pressure.

"If you're trying to go out of your way to appeal to the judge, you're probably going to fail," he said.

Your best selling point has to be "something in you," he says. "And if you try too hard it always works against you.

"You want to be yourself, but you want to have some sort of something that distinguishes you from someone else.

"We live in a time when different is good," says the record exec. "But it's still all about fitting in."

Most important the experts say is never to forget that the show is all about the business of selling music.

"The goal here is to find the next big pop idol -- it's about achieving radio exposure," Leeds said.

So what about that new judge?

Officials yesterday refused to confirm that Martinez had been signed yet.

But she seems to be an easy fit. The sexy hip-hop star released her first solo album "Up Close and Personal" last year and followed it up with a sophomore effort "Animal House" last August.

Her first album earned Martinez a nomination for best female hip-hop artist at the 2002 BET Awards.

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