Speaking to Sci Fi Wire, he told fans to dismiss speculation linking Star Trek's Chris Pine and The Hangover's Bradley Cooper to the lead role of Hal Jordan, claiming the reports were "all false".
"They're all false insofar as we haven't chosen anyone yet. They're still in the negotiations, you know? There's a lot of names being talked about, and there's a lot of people being met, and a lot of... actors reading the script," he said.
Guggenheim went on to assure fans that his adaptation will be faithful to the source material. "The goal here is to do the best cinematic representation of the Green Lantern character," he added.
"You know, there's no desire on anyone's part to completely change the character and just call this other character Green Lantern and try to... draft off the name recognition. This is all about, 'How do we bring the best version of this character to the silver screen?'"
Green Lantern will arrive in cinemas on June 17, 2011.