There’s only one question as " Iron Man 2" debuts this weekend: Will it post a record for an opening weekend, or merely be one of the biggest?

Pre-release surveys indicate that moviegoer interest in seeing the sequel to Marvel Entertainment’s 2008 superhero hit starring Robert Downey Jr. is in the stratosphere.

Opening-weekend ticket sales of at least $140 million seem assured, people who closely follow tracking predicted, and “Iron Man 2" has a good shot at grossing as much as $160 million.

The biggest previous domestic first weekend was “The Dark Knight,” which opened to $158.4 million in 2008. Ticket prices have risen substantially since then, however, so although “Iron Man 2" could post the biggest opening ever in raw dollars, it’s much less likely to do so when accounting for inflation.

Unlike the most successful movies of 2010 to date — “Avatar,” “Alice in Wonderland,” “How to Train Your Dragon” and “Clash of the Titans” — “Iron Man 2" is not being shown in 3-D, so its box-office total won’t benefit from ticket price surcharges of more than $3.

Although “Iron Man 2" has a shot at setting a box-office record for the weekend, it’s less likely to post a Friday record. The movie doesn’t appear to have enough rabid fans panting to see the first possible show. Online pre-sales — typically a good indicator — aren’t even among the top 25 of all time on ticketing websites Fandango and MovieTickets.com.

As a result, debut midnight screenings Thursday night are expected to generate only a few million dollars. “The Twilight Saga: New Moon,” by way of comparison, took in $26 million.

“Iron Man 2" had grossed $133 million from the 53 foreign markets where it opened last week through Wednesday. This week it debuts in four more foreign countries: China, Finland, India and Turkey. The combined worldwide gross is likely to exceed $300 million by Sunday, putting the movie on track to be a financial juggernaut for Marvel and its parent, Walt Disney Co. Paramount Pictures gets

8% of revenue for distributing the film after theaters take their share of ticket sales.

The movie cost about $170 million to produce, and worldwide print and advertising costs are roughly $150million, people familiar with the situation said.

Only one new movie is going up against “Iron Man 2,” and it’s not exactly looking for the same-caliber opening. Universal Pictures’ independent division Focus Features will launch the documentary “Babies,” which tells the story of four infants in different parts of the world, in 534 theaters. That includes a mix of art-house theaters and multiplexes in big cities and suburbs.

Focus is hoping that the movie will take in several million dollars by appealing to a mix of traditional documentary fans as well as families drawn to the picture’s adorable little stars.

“You couldn’t get better counterprogramming against ‘Iron Man’ than this, and you couldn’t find a movie better for Mother’s Day than one about babies,” Focus distribution President Jack Foley said.

ben.fritz@latimes.com