In what is certain to be one of this year's most vigorously debated Oscar battles, the lead actress category is shaping up as a fight between gossamer youth and hard-won Hollywood experience.

Representing the establishment are Meryl Streep and Helen Mirren. Streep — who portrays chef Julia Child in "Julie & Julia" — is a 16-time Academy Award nominee (with two wins). And Mirren, the 64-year old co-star of the Tolstoy biopic "The Last Station," is no less than a Dame Commander of the Order of the British Empire who claimed a lead actress Oscar for portraying her country's monarch in 2006's "The Queen."

In the other corner are two newcomers: Carey Mulligan and Gabourey "Gabby" Sidibe. Mulligan, 24, is a British ingenue most American audiences couldn't have picked out of a police lineup before she appeared as a '60s-era schoolgirl swept off her feet by a dashing older man in "An Education." And portraying an illiterate Harlem teenager with two children sired by her own father, Sidibe, 26, became the unlikely breakout star of "Precious: Based on the Novel 'Push' by Sapphire," landing an Oscar nod for her debut acting role.

"I don't come from a place of film," Sidibe said. "I never paid attention to what kind of roles get nominated for Oscars. I don't have another experience to judge it from."

Of her maiden film experience, the actress exclaimed: "I was just trying to get through the day!"

Then there's the outlier: the dark horse who stands a solid chance at late-inning Oscar redemption after racking up Golden Globe and Screen Actors Guild Award wins. That's first-time Oscar nominee Sandra Bullock, long one of the A-list's most populist actresses. She plays an iron-willed evangelical Christian who takes an African-American football player into her family in the surprise box-office smash "The Blind Side."

On Tuesday morning, Bullock was delighted to be on the Oscar ballot but denied ever having harbored award-season ambitions. "If you look at my choices, I would have made drastically different choices (in my career), if that's what I was going for," she said. "I never aspired to this path."

For her part, Mulligan registered her nomination Tuesday with unmitigated shock — as well as some awe at being classed with Streep and Mirren. "It feels like there should be separate categories for those people and they should get a double Oscar or something," Mulligan gushed. "It's so mad, because they're light-years away — honestly, they're people I've looked up to forever and ever, true idols of mine. I go bright red in the face and mumble every time I see them."