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The shape-shifting robots of "Transformers" have taken on a new form: Huge piles of cash.

The sci-fi saga "Transformers," DreamWorks and Paramount's big-screen take on the Hasbro toys, debuted with $67.6 million in its first weekend and $152.5 million since opening with preview screenings Monday night, according to studio estimates Sunday.

If weekend figures hold when final numbers are released Monday, that would give "Transformers" the biggest first week ever for a non-sequel on a dollar basis, surpassing the $151.6 million of 2002's "Spider-Man." But factoring in today's higher ticket prices, "Spider-Man" drew more people in its first week, about 26.1 million, compared to 22.5 million for "Transformers."

Directed by Michael Bay, "Transformers" features a cast led by Shia LaBeouf and Megan Fox, who are among the humans hurled into the action when two races of warring robots bring their feud to Earth.

The movie's striking visual effects and the affection people have for the Transformers brand — which debuted in the 1980s with toys, a TV show and an animated movie — proved irresistible for audiences, said Rob Moore, Paramount's head of worldwide marketing and distribution.

"Michael Bay created something visually that people hadn't seen before," Moore said. "When you look at a jet plane flying under a bridge then flipping and turning into a robot, those kinds of images people found incredibly unique and compelling."

"Transformers" also is off to a good start overseas, taking in $93.6 million in 23 other countries where it has opened since June 28.

Despite big numbers for "Transformers," the overall domestic box office plunged. The top-12 movies took in $161.5 million, down 23 percent from the same weekend last year, when "Pirates of the Caribbean: Dead Man's Chest" opened with what was then a record weekend of $135.6 million.

After a blockbuster opening in May, Hollywood revenues have dipped, with attendance trailing last summer's. Studios are offering a stronger late-summer lineup than usual, though, including "Harry Potter and the Order of the Phoenix," which opens Wednesday.

"The good news is we've got another big one right around the corner with 'Harry Potter,"' said Paul Dergarabedian, president of box-office tracker Media By Numbers. "We should be looking at a strong midsummer boost that'll hopefully carry through to the end of summer."

The weekend's other new wide release, the Warner Bros. comedy "License to Wed," premiered in fourth-place with $10.4 million, raising its total since debuting Tuesday to $17.8 million. The movie stars Robin Williams as a minister who forces an engaged couple (Mandy Moore and John Krasinski) through a tortuous marital boot camp.

The previous weekend's No. 1 flick, Disney's animated tale "Ratatouille," dropped to second place with $29 million, raising its 10-day total to $109.5 million. "Ratatouille" held up well in its second weekend as revenues fell just 38 percent, compared to drops of 50 percent or more for many other big summer movies.

With a $3 million weekend, Disney's "Pirates of the Caribbean: At World's End" climbed to $301.7 million domestically, following Sony's "Spider-Man 3" and DreamWorks Animation's "Shrek the Third" as $300 million hits this year.

In limited release, MGM's "Rescue Dawn" debuted strongly with $104,000 in six theaters. Directed by Werner Herzog, the film stars Christian Bale in the real-life story of a U.S. pilot struggling to survive after he's shot down over Laos during the Vietnam War.

Fox Searchlight's bad-seed drama "Joshua" opened with $51,086 in six theaters. The film stars Sam Rockwell and Vera Farmiga as parents with a diabolically evil young son.

Warner Independent's "Introducing the Dwights," an Australian comedy centered on an aging standup comic (Brenda Blethyn) whose comeback attempt disrupts her shy son's new romance, debuted with $31,000 at four theaters.

All three films expand to more theaters Friday.

Estimated ticket sales for Friday through Sunday at U.S. and Canadian theaters, according to Media By Numbers LLC. Final figures will be released Monday.

1. "Transformers," $67.6 million.

2. "Ratatouille," $29 million.

3. "Live Free or Die Hard," $17.4 million.

4. "License to Wed," $10.4 million.

5. "Evan Almighty," $8.1 million.

6. "1408," $7.1 million.

7. "Knocked Up," $5.2 million.

8. "Fantastic Four: Rise of the Silver Surfer," $4.15 million.

9. "Sicko," $3.65 million.

10. "Ocean's Thirteen," $3.5 million.