The romance starring Jason Segel and Emily Blunt, made by the same team behind hit "Forgetting Sarah Marshall," kicked off the festival which is entering its second decade with organizers promising a broad group of films from all regions of the world.

Segel and Blunt hit the red carpet for the movie in which they portray a couple discovering each other during a never-ending engagement. The film is directed by Nicholas Stoller, who co-wrote the script with Segel. The pair first teamed up with on the 2008 blockbuster "Marshall."

"This is how inertia can destroy a relationship," Stoller told Reuters. "They realize that they didn't know each other quite as well as they thought. It's about how an engagement can get in the way of a relationship."

Compared to "Marshall," the characters are slightly older and the male and female perspectives on love and relationships were equally represented, said Stoller. But his new film offers the same honesty as "Marshall" and "Get Him to the Greek," which he also co-wrote with Segel.

"We like things to be awkward and real like they are in real life. People don't often come out with the perfect phrase to explain a moment," he said. "That kind of awkwardness and reality makes for the best comedy because people can see themselves in the characters."

On the red carpet, Segel described the movie as "a lean mean comedy machine," and joked that, like his previous comedies, there were again plenty of scenes of himself nude in strange situations. "Sadly, sadly there is, yes," he said.

Blunt said another film in which she stars here at Tribeca, "Your Sister's Sister," is far different from the comedy opposite Segel, whom she described as a "good pal."

"This is a big raucous comedy and the other one is a tiny movie all improvised, made for no money. We shot it in 12 days - there are very diverse, which at least is a good thing," she said.

The film's producer Judd Apatow, actress Olivia Wilde, comic actresses Amy Poehler and Julia Louis-Dreyfus, documentary maker Michael Moore, as well as the festival's co-founder Robert De Niro also attended the opening, held not far from Central Park.

De Niro helped set up the festival as a way to revive downtown Manhattan after the September 11 attacks, and many of the screenings are still held in downtown Manhattan.

This year, Tribeca will screen 89 feature films split between 57 fiction and 32 documentaries, including 50 world premieres.

It is the first year Tribeca organizers selected debut night films for the narrative and documentary competitions, and organizers said the overall program reflects a range of films from around the world. Half of the festival's lineup of 12 fiction films in competition are international productions.

The festival will return to more bigger-budget Hollywood fare for its closing night film, the anticipated superhero blockbuster "The Avengers," to be screened on April 28.

(Additional reporting by Alicia Powell, Editing by Bob Tourtellotte)

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