The November sweeps are upon us. Prepare to be entertained! Or maybe not. Over the next month, the networks will pull out the stops to increase ratings share, an all-important measure in determining the money they can charge to air commercials.

Thursday nights are the most crucial to both networks and advertisers because they soften up consumers just before the weekend, when, it is presumed, we are unconstrained from the confines of work and left free to spend with wild abandon. And since most major motion pictures open on Friday night, Thursday is a perfect night to advertise new movies.

As it has for some time now, Thursday nights belong to CBS. Americans can’t get enough “CSI” (8 p.m., CBS). In fact last week, CBS aired a repeat of the mortuary mystery and that was the number one broadcast of the week. With popularity like that, you don’t need gimmicks or stunt-casting, so look for run-of-the mill morbidity on “CSI” tonight, when the reasons behind a woman’s death, first reported to be a suicide, turns out to be a little more sinister.

The sweeps stunts begin in earnest on “Without a Trace” (9 p.m., CBS) when Jack and Danny travel to Mexico to investigate the case of an American tourist abducted in front of his wife (Alex Kingston). Savvy viewers know that Kingston used to star as Dr. Elizabeth Corday on NBC’s “ER.” But will they care? Is this just a case of one network (CBS) thumbing its nose at another (NBC) and hoping to steal viewers from its formerly top-rated rival? In case you have any doubt, tonight’s episode is directed by Paul McCrane, who played Dr. Robert Romano on “ER.”

Tonight’s other highlights

¢ Jeff Probst hosts “Survivor: Guatemala” (7 p.m., CBS).

¢ Sandy supports Ryan’s new move on “The O.C.” (7 p.m., Fox).

¢ Julius and Rochelle hire a babysitter on “Everybody Hates Chris” (7 p.m., UPN).

¢ Jason Biggs guest stars on “Will & Grace” (7:30 p.m., NBC).

¢ Having fired four wannabes last week, Donald Trump returns to “The Apprentice” (8 p.m., NBC).