ROME - Alfonso Cuaron's 3D sci-fier "Gravity," toplining George Clooney and Sandra Bullock, will open the 70th Venice Film Festival, marking the first time the Lido kicks off with a 3D pic.

The buzzed-about Warner Bros. pic will world preem on August 28 out-of-competition in the Sala Grande, getting Venice off with a bang.

Venice previously bowed with a sci-fi pic, albeit one with less gravitas, in 2000 with Clint Eastwood's "Space Cowboys," during current Venice topper Alberto Barbera's previous mandate as artistic director.

In "Gravity," Bullock plays Dr. Ryan Stone, a medical engineer on her first shuttle mission with veteran astronaut Matt Kowalsky (George Clooney). On a seemingly routine spacewalk, disaster strikes. The shuttle is destroyed, leaving Stone and Kowalsky completely alone - tethered to nothing but each other and spiraling out into blackness, according to press notes.

Pic is penned by Alfonso Cuaron and Jonas Cuaron and produced by Alfonso Cuaron and "Harry Potter" series producer David Heyman.

Cuaron is a Venice aficionado. His "Y tu mamá también" won the Lido's Golden Osella for Best Screenplay in 2001. In 2006 his "Children of Men" took the Golden Osella for Best Cinematography, honoring Emmanuel Lubezki, who is also the director of photography on "Gravity."

The 70th edition of Venice will run August 28 to September 7.