In an interesting box office showdown, Paramount’s much-hyped monster movie “Cloverfield” and 20th Century Fox’s romantic comedy “27 Dresses,” starring Katherine Heigl, open this weekend in what looks to be a battle of the sexes.

Release of the J.J. Abrams-produced “Cloverfield” is a defining moment for Brad Grey’s Paramount, which needs a hit of its own after it was largely propped up by DreamWorks titles in 2007.

Pic is bowing in 3,441 theaters –the most ever for a January opening. Fox isn’t fooling around either. “27 Dresses” opens in 3,057 runs, one of the highest numbers for this time of year.

Par is counting on its 2008 slate to reinvigorate the Melrose lot, beginning with “Cloverfield,” whose novel approach to the classic monster-demolishes-Gotham motif is sure to pique the interest of younger males.

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Par was none too happy when Fox decided late in the game to delay “27 Dresses” by one week to today. It was a smart move for Fox, which wanted to give some breathing room to Fox Searchlight’s teenage dramedy “Juno,” which has been on a box office roll.

“Cloverfield” was already tracking poorly among women, and “27 Dresses” only exacerbated the problem. Latter also stars James Marsden and Edward Burns.

Nor was Overture Films too pleased by the move. It will release its first movie this weekend, the female-skewing crime caper “Mad Money,” starring Diane Keaton, Queen Latifah and Katie Holmes. Pic bows in 2,470.

Most box office forecasters believe “Cloverfield” will win the four-day Martin Luther King holiday weekend. Pic has been picking up some interest among younger females in recent days, although women still heavily favor “27 Dresses.”

One studio exec noted that the “swing vote could be the 35-year-old couple who goes to the movies Saturday night. Which film are they going to see, ‘Cloverfield’ or ‘Dresses’?”

Overture said “Mad Money” appeals to older women, while “Dresses” is skewing younger.

The Martin Luther King holiday isn’t known for big box office grosses. The holiday weekend’s highest-grossing pic is Ben Stiller-Jennifer Aniston comedy “Along Came Polly,” whose opening three-day gross was $27.7 million, while its four-day holiday gross was $32.4 million.

Many estimate that “Cloverfield” and “27 Dresses” will be strong performers for the frame.

Paramount played it smart in spending only $25 million to produce “Cloverfield”; the movie won’t need a huge opening or mega-grosses. With the pic shot in hand-held camera style and starring an unknown cast, plenty of money was left over for special effects.

What Par does need is to win the perception game, in which the nuances of how much a movie cost in relationship to its B.O. performance doesn’t always matter. And Paramount clearly needs to avoid losing the weekend to “27 Dresses.”

Par execs have been aggressively seeking to manage expectations for “Cloverfield.” There could be more upside for the pic considering that younger males may not be picked up by tracking. Also, Par has used guerrilla tactics in marketing the monsterfest, including keeping the name and storyline top secret.

On the specialty side, the Weinstein Co. opens Woody Allen’s sibling crime drama “Cassandra’s Dream,” toplining Ewan McGregor and Colin Farrell, in 107 theaters.

Roadside Attractions releases “Teeth” in four. Pic bows a year after it was acquired at the Sundance Film Festival by Lionsgate and the Weinstein Co. Lionsgate recently pacted with Roadside.

On the foreign front, “I Am Legend” looks likely to score its fifth straight weekend win. The Will Smith actioner’s opening in Brazil and Mexico and should crack the $250 million mark in international grosses during the frame.

Given its strong holdover performances and Smith’s star power, “Legend” could wind up its foreign run near $400 million for Warner Bros.

Paramount’s decided to go day-and-date in Australia, Hong Kong and New Zealand with “Cloverfield.” Studios have been employing day-and-date releasing more often in Oz, where audiences tend to mirror the tastes of domestic moviegoers.

Fox expands “Aliens vs. Predator — Requiem” into South Korea and the U.K. after racking up about $60 million from its early foreign run. Studio’s also taking “Alvin and the Chipmunks,” with nearly $90 million banked overseas, into Italy.

Awards-season fare will see their releases widened. Universal, for example, is opening “Charlie Wilson’s War” in France and Switzerland. Wednesday grosses on opening day in France looked moderate at $273,165.

U’s also opening “Atonement,” which has $44 million overseas, in Russia and Ukraine. Fox is launching “Juno” in Australia, and Par’s expanding “The Kite Runner” into Australia, Brazil, Germany and “No Country for Old Men” in the U.K.

(Dave McNary contributed to this report.)