NEW YORK - With some jurors nodding their heads to the beat, lawyers sparred over whether rappers Ludacris and Kanye West stole the essence of another song to create the 2003 hit "Stand Up."

The jury in U.S. District Court in Manhattan listened to the song and "Straight Like That" by a group called I.O.F. from East Orange, N.J. Two of the 10 jurors nodded their heads to the beat of Ludacris' song but were still during the little-known track.

Attorney Mel Sachs said he will prove Ludacris heard the song before he made his breakthrough hit, even though "Straight Like That" never made it beyond some air time on college radio after it was released in September 2001.

Hundreds of promotional copies of "Straight Like That" were distributed, Sachs said, and the New Jersey company that produced the song was contacted by one of Ludacris' record companies.

At issue are the words "like that," repeated more than 80 times in each song, though one song precedes the phrase with "straight" while the other precedes it with "just," Sachs said.

The plaintiffs were trying to claim rights to the words "like that," said Christine Lepera, attorney for the rappers and EMI April Music Inc.

"None of you can monopolize certain expressions," she said, urging the jury to reject the claims of BMS Entertainment/Heat Music LLC.

Ludacris and West first heard "Straight Like That" when the lawsuit was filed, she said.

Sachs asked the jurors not to be "blinded by celebrity."

Ludacris, whose real name is Chris Bridges, has been praised for his music and his acting roles as Anthony in the Oscar-winning "Crash" and as Skinny Black in "Hustle and Flow."

West has won six Grammy Awards for his two multiplatinum albums, "The College Dropout" and "Late Registration." Also known for speaking his mind, he said President Bush "doesn't care about black people" during a telethon for Hurricane Katrina victims.

Both are expected to testify, but West wasn't in the courtroom Tuesday and Ludacris declined to comment.

The trial, expected to last a week, will determine liability. If liability is found, a second phase will assess damages.