Back in August, Marvel Studios officially announced that Bradley Cooper had been cast as Rocket Raccoon in Guardians of the Galaxy. Because Rocket Raccoon will be a CGI character in the film, it was unclear exactly when Bradley Cooper would do his voice work for the character. While Guardians of the Galaxy has been filming in London for the last couple months, there have been no reported sightings of Bradley Cooper on set that we're aware of. However, when director James Gunn was asked earlier today whether Bradley Cooper had begun his work on Guardians of the Galaxy, Gunn replied, "Yes he has. He's awesome." No further information was provided, so it's unclear as to what location he might be doing his voice work from. Vin Diesel is reportedly going to be playing Groot, who is the other major CGI character in the film, but he is currently filming for Fast & Furious 7. Gunn has also recently been singing the praises of several of his actors on Twitter. In late September, Gunn tweeted, "Today the performances of @prattprattpratt @zoesaldana @DaveBautista & @Thejudgegunn made me tear up. From my heart, they are all amazing." In early October, Gunn added, "Today @Michael_Rooker swallowed this scene like a boa would a baby rabbit. I can't wait for you guys to meet Yondu. Wow." Guardians of the Galaxy is set to be released in movie theaters on August 1, 2014.