After reporting earlier today that Natalie Portman would not star in Gravity, Variety is now telling us that Sandra Bullock is in heavy talks for the lead role.

The studio certainly seems to be moving fast on the Alfonso Cuarón project, which he will direct from a script he co-wrote with his son, Jonás Cuarón. It wasn't said when Warner Bros. and Sandra Bullock entered into discussions for the movie, and the site reports that Natalie Portman left the project only because of scheduling conflicts.

RELATED: NASA Astronaut Tears Into Gravity, He Thinks It Bad for Little Girls

Robert Downey Jr. remains attached to Gravity in a smaller role, with the story centering on the female lead, who is trying to make it back home to her daughter after debris from a satellite takes out the entire crew of her space station.

No production schedule was released for Gravity, although, with Warner Bros. acting so quickly to land their female lead, the movie will likely go into production sometime before the end of the year.