Acclaimed director Ang Lee has unveiled his latest movie, Lust, Caution, at the Venice Film Festival.
The Taiwanese film-maker is hoping to replicate the success he had with Brokeback Mountain, which scooped the festival's top prize two years ago.
Lust, Caution, a wartime thriller, has been given a restrictive NC-17 rating in the US for its explicit sex scenes.
But critics in Venice say the film is "too cautious" and "risks leaving audiences cold".
Trade paper Variety said the Chinese-language film "lacks the deep-churning emotional currents that drove Lee's Brokeback Mountain and his best other works".
It predicted modest box office returns for the film when it opens in the US at the end of September.
Further premieres follow at the Italian festival on Friday, including George Clooney's forthcoming thriller, Michael Clayton.
Lee defended his film's explicit sex scenes
In it, Clooney play the "fixer" for a New York law firm, who is tasked with covering up corporate dirty work.
Director Brian De Palma's hard-hitting Iraq drama, Redacted, will also receive its world premiere.
It tells the true story of a group of US soldiers who raped and murdered of a 14-year-old Iraqi girl in Mahmudiya last year.
Shown through the imaginary video lens of one of the soldiers involved in the raid on the girl's home, the dramatisation is interlaced with actual news clips, documentary footage and stills from the war.
"The true story of the Iraq war has been redacted from the mainstream corporate media," said De Palma, who is best known for movies like Carrie, Scarface and The Untouchables.
"If we are going to cause such disorder, then we must face the horrendous images that are the consequences of these events."
While Clooney and De Palma are both expected to arrive in Venice to promote their films, fellow Hollywood star Scarlett Johansson has cancelled her appearance.
The Lost In Translation actress had been expected in Venice for the screening of her new film The Nanny Diaries, but she pulled out at the last minute, citing work commitments in the US.
Lee's Lust, Caution is based on a novella by the famed Chinese writer Eileen Chang.
It follows a Chinese woman in Japanese-occupied Shanghai during World War II, who finds herself in the centre of a plot to seduce and kill a married enemy collaborator.
The cast includes newcomer Tang Wei and Tony Leung, one of China's biggest stars, as well as pop star Leehom Wang.
On arrival in Venice, Lee defended the film's sex scenes and said he hoped the NC-17 rating would not discourage audiences.
"We hope to send the message in the US that NC-17 is a respectable category," he said.
"It's not pornography. It's just unsuitable for children."
Lee also addressed an outcry over the film's listing in the festival programme - which described it as originating from Taiwan, China.
He called the incident, which has angered Taiwanese authorities, "unfortunate", but said he was at a loss to explain the error.
"If you can find out what's going on, please let me know," he told reporters.
China and Taiwan set up separate governments in 1949, but Beijing still considers Taiwan as part of its territory.