Speaking with Newsarama, Chris explained that he had been shocked to discover they were both auditioning for the same part.
"[Liam and I] both auditioned for it funnily enough," he said. "The next minute I heard they were flying Liam over to meet with Kenneth [Branagh]."
Once he also received the call to meet with Branagh, Chris admitted that he turned to his younger brother for advice but did not go on to explain why he eventually secured the role over Liam.
Thor will be released in summer 2011, following which Chris will star in 2012's The Avengers.