ZHANG Ziyi is an international film star, spokesmodel for Maybelline cosmetics and Pantene shampoo, Oscar presenter and a frequent finalist on lists of the world’s most beautiful women.

Stardom like that would give many an actress a swelled head.

Not 26-year-old Zhang, who out of the spotlight maintains a bubbly, girl-next-door innocence and seems genuinely surprised at her success.

Several times during an interview with The Post, she expressed amazement that world-class directors like Zhang Yimou, Ang Lee and Wong Kar-wai “trust me.”

“I was shocked [that I did so well],” the Beijing-born cutie said of her work in Wong’s “2046,” in which she plays a prostitute. (It opens here Friday.)

“At the beginning, I was so nervous because we didn’t have a script and I wasn’t sure about my part.

“But I was excited to work with him [Wong]. He’s so talented I hoped I could grab something from him.

“When I watched the movie, I was shocked because I realized I can do such difficult roles. I can handle it.”

The Hong Kong film – beautifully shot by Wong’s longtime cinematographer, Aussie bad boy Christopher Doyle – has been the subject of hot buzz ever since it debuted at Cannes 2004.

It features an all-star Chinese cast: In addition to Zhang, there are Wong regulars Tony Leung and Maggie Cheung, who co-starred in his 2000 film “In the Mood for Love”; Cantopop sensation Faye Wong, star of his 1994 “Chungking Express”; and Gong Li (“Raise the Red Lantern”), in her first film with the director.

Zhang was discovered by “Lantern” director Zhang Yimou (no relation) at a Beijing casting call for a shampoo commercial.

The ad was never made, but the famed filmmaker was so impressed with the teenager that he cast her in a tear-jerker called “The Road Home.”

“It’s my favorite role,” the actress said. “And ‘2046’ is my most difficult.”

In 2000, she got her first taste of international stardom, playing a precocious assassin in Lee’s popular martial-arts epic “Crouching Tiger, Hidden Dragon.”

Her first U.S. movie was 2001’s “Rush Hour 2,” with Jackie Chan. She spoke no English, so Chan had to translate everything the director said.

She’s since worked hard to learn English. During our interview, she answered most questions without help from a translator.

But she’s still not satisfied. She’ll be staying in New York for a month taking an English course in the Empire State Building.

“I have lots of homework to do,” she confessed.

Zhang said she has no time for hobbies, but if she did, she’d “stay at home and watch movies and eat some snacks and decorate my house with new furniture.”

Americans will soon see her in Rob Marshall’s “Memoirs of a Geisha,” based on the popular novel by Arthur Golden. It could raise her profile among mainstream U.S. audiences.

She’ll play one of Japan’s leading ladies of pleasure, which, in addition to the language hurdle, presents another acting challenge.

“It’s difficult for Chinese to play Japanese roles because we have totally different cultures,” Zhang said of “Geisha.” “We have to learn from the beginning how to walk in a kimono, how to bow, how to kneel. I hope that when people see the movie, they’ll say I look Japanese.”

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