NEW YORK — Jennifer Lopez is on top of the movie and music charts, but will she mount the witness stand in her ex-boyfriend's trial?

The question has dogged Sean "Puffy" Combs' defense since before the trial opened, and the rap mogul's lead lawyer, Benjamin Brafman, claims his office fields 500 to 600 calls a day on that very question. The answer? A coy "It's possible" is all the defense camp will offer.

The intrigue will end this week. Combs' defense will rest by Friday, and Lopez, who has repeatedly said through her lawyer that she will testify if asked, is back in New York after a promotional tour in Australia.

But in deciding whether to call her, the defense has to weigh more than her availability. Lopez seems a strong witness for Combs. Not only was she present for the 1999 club shooting and aftermath that landed Combs in jail, but she is beautiful, articulate and convinced he is innocent. Putting her on the stand, however, is not without serious risks.

Her grand jury testimony, for example, could prove problematic if she testifies. Lopez went before the panel just three days after the shooting at Manhattan's Club New York and reportedly assured jurors that Combs was unarmed that night. She recalled dancing with Combs, hugging him and even watching him get dressed and said he simply did not have a gun. According to the defense, she completely exonerated Combs.

But her testimony wasn't enough to convince the 23 grand jurors. Just two weeks later, they indicted Combs on weapons possession charges. A bribery count followed. Although the standard of proof in a trial is much higher than in a grand jury, Combs' lawyers have to consider whether Lopez will make a credible witness. With Combs already accused of bribing his chauffeur and another key witness in the case, the defense does not want appear to be calling witnesses who tailor their testimony to help the powerful defendant.

At the same time, the prosecution will certainly attack Lopez if she strays at all from her grand jury testimony. And that could be a serious test of her memory. Lopez spent hours before the grand jury detailing what she did and saw on Dec. 26 and Dec. 27, 1999, but unlike prosecution witnesses, who are often provided transcripts of their testimony to refresh their memories, Lopez as a defense witness has never reviewed her account of that night. If 14 months later, her account is at all different, expect the prosecutor to pounce.

Assistant District Attorney Matthew Bogdanos has already used grand jury minutes to dismantle the testimony of Curtis Howard, Combs' security guard. Howard was called by the prosecution, but Bogdanos refused to let the witness read his grand jury testimony before testifying, saying the defense might use it as a "road map to perjury."

Repeatedly, Bogdanos implied that discrepancies between the grand jury and trial testimony were proof that Howard was not telling the truth in a bid to help Combs.

Despite the drawbacks, the defense appeared to open the door for Lopez to take the stand two weeks ago when chauffeur Wardel Fenderson gave devastating testimony against Combs. Fenderson said the music executive offered him $50,000 to take the gun possession charge while he, Lopez and Combs were in police custody. According to Fenderson, Lopez was just two feet away from her then-boyfriend when Combs suggested his driver take a diamond-encrusted pinkie ring, a gift from Lopez, as collateral. If Lopez was so close and did not hear a bribe, her testimony could be crucial to the defense.