If I'm correct about who'll win best supporting actor and actress — George Clooney ("Syriana") and Rachel Weisz ("The Constant Gardener") — one factor will probably play a starring role: the fact that both artists really portray lead characters.

It's one of the oldest tricks in the Oscar book: if you're a lead actor who wants to win bad enough, just swallow hard, slip down into that supporting category and you'll probably clobber all rivals just based on screen time alone. Consider a few of the many examples of supporting-acting winners who arguably were leads on screen: Jennifer Connelly ("A Beautiful Mind"), Angelina Jolie ("Girl, Interrupted"), Kevin Spacey ("The Usual Suspects") and Tatum O'Neal ("Paper Moon").

Clearly, there was no female star who upstaged Eva Marie Saint in "On the Waterfront" as she battled with Marlon Brando, who famously pleaded with her in their big knockout scene, "You love me! I want you to say it to me!" She won that supporting Oscar for the haunting way she delivered her doomed reply: "I didn't say I didn't love you! I said, 'Stay away from me!'"

What all of those champs had in common was that they were relative unknowns when they won. Many Oscar strategists believe it's wise for rookies to campaign in that second tier, even when they actually have more screen time than celebrity costars who get nominated in a lead category. That strategy paid off for Timothy Hutton (his "Ordinary People" costar Mary Tyler Moore lost best actress), Haing S. Ngor ("The Killing Fields" costar Sam Waterston lost best actor) and Jim Broadbent ("Iris" costar Judi Dench lost best actress).

When celebrities try that same ploy, it sometimes backfires. Poor Ethan Hawke actually had the most dialogue and face time in "Training Day," but agreed to step down to the supporting slot so he wouldn't compete opposite costar Denzel Washington, who'd already won that race ("Glory"). Ethan ended up losing while Denzel nabbed Oscar No. 2. Anthony Hopkins and Nicole Kidman only had minimal screen time in, respectively, "The Silence of the Lambs" and "The Hours," but they refused to lower themselves to supporting status and prevailed in lead anyway.

Technically, it doesn't matter which Oscar race you campaign for — voters decide where to put you and they've been known to disagree with choices made by some contenders. Benicio Del Toro ("Traffic") won lead actor at the SAG Awards, but was placed in the supporting race at the Academy Awards, which he also won. Thirteen-year-old Keisha Castle-Hughes was obviously the lead in "Whale Rider," but she campaigned in supporting because that's where academy voters always put kids — except, egads, then. They shocked Keisha by making her the youngest person ever nominated for best actress.

This year Jake Gyllenhaal had a tough time deciding where to compete. Early in Oscar season he declared himself for supporting for "Brokeback Mountain" because it looked like he could be nominated in the lead category for "Jarhead." When "Jarhead" tanked, the Golden Globes put Jake in lead contention for "Brokeback," but he got snubbed due to the glut of major guy performances this year. Lucky for Jake, Oscar voters pushed him back down to supporting where he nabbed a nom. Considering his recent win at the BAFTA Awards and the fact that his movie is the front-runner to win best picture, Jake has a real shot at winning on March 5.

But he must get around Clooney, who also had trouble deciding which race to run in. At first his Oscar strategists decided the issue for him and put him in supporting. When Clooney got wind of it, he disagreed and publicly declared himself in lead. An outcry followed. The "Syriana" star listened carefully to all of the arguments uttered by experts and wisely switched back to supporting. Even if Jake or Paul Giamatti ("Cinderella Man") beat him, it's unlikely that he could beat Philip Seymour Hoffman ("Capote") for best actor.

Photo: Anne Baxter (right, rear) probably would've won best supporting actress of 1950 for "All About Eve," but she acted too much like her screen role as an ingénue hell-bent on upstaging a veteran showbiz diva. Citing the fact that her character's name is in the title of the film, she insisted on campaigning for best actress opposite Bette Davis. Both got nominated and lost when the costars canceled each other out.
(20th Century Fox)