Oscar loves a feel-good underdog, which accounts for much of the momentum of “Slumdog Millionaire.”

Oscar is fond of washed-up stars who make comebacks and straight actors who play gay characters, which means a close race for best actor between Mickey Rourke of “The Wrestler” and Sean Penn of “Milk.”

Oscar tends to reward those who’ve racked up several previous nods with no wins, which is good news for best-actress nominee Kate Winslet of “The Reader.”

And Oscar has a thing for Woody Allen’s actresses, which should convince Penelope Cruz of “Vicky Cristina Barcelona” to have an acceptance speech ready for best supporting actress.

Of course, when the statuettes are handed out, it could be an evening of historic upsets. I’m not betting on that, and neither are leading-role nominees Richard Jenkins and Melissa Leo and supporting-role nominees Taraji P. Henson and Michael Shannon, four contenders considered the longest of shots.

Still, stranger things have happened at the Oscars. Remember Sacheen Littlefeather and the streaker?

Gazing into Oscar’s crystal ball is one of the true pleasures of the awards season. Who’ll win? Let’s review the conventional wisdom on the major categories.

BEST PICTURE
“The Curious Case of Benjamin Button”
“Frost/Nixon”
“Milk”
“The Reader”
“Slumdog Millionaire”

Will win: Although “Benjamin Button” grabbed the most nominations with 13, “Slumdog Millionaire” is the one to beat. The little Cinderella story that’s become a cultural phenomenon manages to combine buoyant optimism (the scenes of the Indian version of “Who Wants to Be a Millionaire”) with unvarnished drama (the glimpse of life in the Mumbai slums). It seems like a perfect fit for this particular moment in our hot, flat and crowded world. Now for the real question: Is it one for the ages or another “Shakespeare in Love,” a crowd-pleaser that’s less admired in retrospect?

BEST ACTOR
Richard Jenkins, “The Visitor”
Frank Langella, “Frost/Nixon”
Sean Penn, “Milk”
Brad Pitt, “The Curious Case of Benjamin Button”
Mickey Rourke, “The Wrestler”

Will win: Mickey Rourke’s triumphant return makes him the frontrunner, but he may be a little too similar to his beat-up character for mainstream voters. Look for Sean Penn to score a minor surprise for his charismatic performance as gay rights leader Harvey Milk. And if neither of them nabs it and Brad Pitt or Frank Langella doesn’t sneak in, how about Richard Jenkins? Unlike the competition, the little-known character actor didn’t play a real-life politician or have an amazing story or get transformed by really cool special effects. He just did his job ... superbly.

BEST ACTRESS
Anne Hathaway, “Rachel Getting Married”
Angelina Jolie, “Changeling”
Melissa Leo, “Frozen River”
Meryl Streep, “Doubt”
Kate Winslet, “The Reader”

Will win: Anne Hathaway is cinema’s new princess, but after six nominations, it’s Kate Winslet’s turn to shine - not for “Revolutionary Road,” where she fearlessly explored the torments of ordinary life, but for “The Reader,” a Holocaust-themed film that’s had critics debating its merits. Winslet’s strongest rival is Meryl Streep, who remains the gold standard of acting. She’s as expressive when she’s cloaked in nun’s garb for “Doubt” as when she’s singing up a storm in “Mamma Mia!” Plus, Streep hasn’t won since 1983, so she’s overdue.

BEST SUPPORTING ACTOR
Josh Brolin, “Milk”
Robert Downey Jr., “Tropic Thunder”
Philip Seymour Hoffman, “Doubt”
Heath Ledger, “The Dark Knight”
Michael Shannon, “Revolutionary Road”

Will win: The consensus is the award will go to Heath Ledger, who died last year before the Batman movie was released. It will be a fitting tribute to the actor, who was in the running for an Oscar in 2006 for “Brokeback Mountain.” But poignancy aside, Ledger’s brilliance as the chaos-craving Joker would be a standout in any year.

BEST SUPPORTING ACTRESS
Amy Adams, “Doubt”
Penelope Cruz, “Vicky Cristina Barcelona”
Viola Davis, “Doubt”
Taraji P. Henson, “The Curious Case of Benjamin Button”
Marisa Tomei, “The Wrestler”

Will win: Although it’s a wide-open contest, Penelope Cruz could join the actresses who’ve been honored for their roles in Woody Allen films (hey, it worked for Mira Sorvino, Dianne Wiest and Diane Keaton). Cruz’s lushly sexy portrayal was nothing we haven’t seen before, but there’s something to be said for playing to your strengths. Still, Marisa Tomei fans want to see the actress win again, this time for her single-mom stripper in “The Wrestler,” a richer turn than her Oscar-grabbing role as a brassy Brooklynite in “My Cousin Vinny.”

BEST DIRECTOR
Danny Boyle, “Slumdog Millionaire”
Stephen Daldry, “The Reader”
David Fincher, “The Curious Case of Benjamin Button”
Ron Howard, “Frost/Nixon”
Gus Van Sant, “Milk”

Will win: Danny Boyle has been noticed before in films like “Trainspotting,” but his fast-paced style goes to deeper places and strikes a universally human chord in “Slumdog.” He’ll probably take the prize, especially if “Slumdog” gets top honors. But there’s an argument to be made for David Fincher. Without his sweeping vision and ability to keep the technical wizardry of “Benjamin Button” from overshadowing the story, the “Forrest Gump”-like fable could have been a mere curiosity.

BEST ORIGINAL SONG
“Down to Earth (“WALL-E”)
“Jai Ho” (“Slumdog Millionaire”)
“O Saya” (“Slumdog Millionaire”)

Will win: “Down to Earth” is the favorite, but Peter Gabriel won’t perform it during the Oscar telecast. Why? He’s protesting the shortening of the three tunes into a medley that allows 65 seconds for each. Gabriel, who’s nominated with Thomas Newman for the song, is expected to attend. Anyone care to ask Rob Lowe and Snow White to take over for him?