Forget basketball — the new March Madness is happening at the movies.

Studios are packing four or more big-budget bets into the month that traditionally has hosted half that many. For the second year in a row, tentpole season starts early, the result of past successes (“Alice in Wonderland” and “300”), a more competitive summer and an expanded crop of awards contenders.

This year’s early bird is Warner Bros.’ $200 million-plus budgeted “Jack the Giant Slayer,” though modest tracking ($25 million-$30 million) poses a steep beanstalk-climb toward profitability. Other wide openers this weekend include Relativity’s “21 and Over” and CBS Films’ “The Last Exorcism Part II.”

Hollywood rolled out the most-ever big-budget tentpoles last March, with four: Universal’s “The Lorax” kick-started the onslaught, followed by Disney’s “John Carter,” Lionsgate’s “The Hunger Games” and Warner’s “Wrath of the Titans.” Only two pics (guess which ones) survived the March invasion.

Now, the same number of tentpoles bow this month, including “Jack,” Disney’s “Oz the Great and Powerful,” Fox-DreamWorks Animation’s “The Croods” and Paramount’s “G.I. Joe: Retaliation.” Open Road also has Stephanie Meyer’s “The Host” later this month.

It’s hard to ignore the comparisons between “Jack the Giant Slayer,” a co-venture involving Warner, New Line and Legendary Pictures, and Disney’s mega-misfire “John Carter.” Both faced hefty production costs (“Carter” cost more, at around $250 million), with pricey marketing campaigns and similar tracking. And like “John Carter” — as with any budget-buster that disappoints at home — “Jack” will rely more than usual on international playability.

Unlike “Carter,” which bowed day-and-date everywhere (except in Japan and China), “Jack” rolls out in a staggered international release, with only smaller Asian territories this weekend.

The emergence of March tentpole season is a multi-faceted product of past successes like “Alice” in 2010 ($334 million domestic) and last year’s “The Hunger Games” ($408 million). And an earlier Oscars ceremony has cleared the month of resilient Academy Awards-nominated fare.

Moreover, the Academy’s expanded best picture category has pushed some studio tentpoles further back to avoid competing with a larger pool of nominees. This year had a record six (potentially seven, with “Zero Dark Thirty”) pic nominees that surpassed $100 million domestic.

While most of those nominees have fallen from the fray, they’re still siphoning eyeballs away from wide releases with less marketing muscle behind them, including “21 and Over” and “The Last Exorcism Part II.” Relativity is mirroring Warner’s release of similarly skewing “Project X” this same weekend last year.

“21 and Over,” which stars twentysomethings Miles Teller and Skylar Astin as college students, should earn between $13 million and $15 million through Sunday. Relativity owns worldwide rights to the $13 million-budgeted film, with production costs covered by foreign pre-sales and output deals.

Meanwhile, “Exorcism” should counter nicely the male-targeted “21 and Over” by appealing to a mostly female crowd. A solid opening would land the scarer at north of $10 million, though the film could see a more modest $8 million opening. CBS Films acquired rights to the sequel for roughly $3 million.

For Warners, exposure on “Jack” is hardly crippling, thanks to financial help from Legendary. But the film may not see the desired results overseas as the story of Jack and the Beanstalk is an unknown property throughout most of Asia. That means Europe will do most of the heavy lifting, a heavy load for the mature continent where there is little room for an upside.

As it affected “John Carter” last year, the overcrowded March pipeline could seriously limit Stateside playability for “Jack,” especially with “Oz the Great and Powerful” treading on its heels next weekend. “Oz” is tracking to earn $60 million-$75 million domestic in three days.

Bowing wide, though not expected to make a major mark, RCR Distribution has Ed Harris-David Duchovny submarine pic “Phantom” at more than 2,000 Stateside locations. Bizzers are calling the aggressively self-distributed effort this year’s “Oogieloves,” but with submarines. That pic was mostly crippled by an oversized budget, however.

Fox Searchlight kick-starts its Stateside run of helmer Chan-wook Park’s stylized suspenser “Stoker” at seven sites in New York, L.A., Chicago, Toronto and Boston.