Los Angeles, Oct 8 (IANS): Sandra Bullock and George Clooney were not the first choice for sci-fi thriller "Gravity" which has opened to a staggering $55.6 million at the US box office. The makers initially wanted Robert Downey Jr. and Angelina Jolie but it didn't work out.

While Downey Jr. was already on board, Jolie had to pass up the project after much thought and owing to a rather busy schedule in 2010, said a statement.

Due to the delay caused by the hunt for the female lead, the dates of the shoot coincided with those of "Iron Man 3" and "Avengers" and with reluctance, Downey Jr. also had to pass up the role.

After this, Natalie Portman and Blake Lively were approached. But Portman was all set to go on her pregnancy break at the time and Lively didn't exactly fit the bill.

Finally, the role landed in Sandra Bullock's lap. As fate would have it, when the shoot was just about to commence Clooney's schedule opened up for a short role in the film.

The film will release in India Oct 11.