At an interview I went on it turned out I was an acquaintance of the hiring manager, although we aren't close enough to be considered friends by any means. Our interview went well, and he said he wanted to hire me because I would be a good fit for the ten person team he is assembling. There is one technical area in which I'm not very knowledgeable, but we both think it's something I can pick up reasonably quickly.
However, after several days passed, instead of sendng a job offer, he told me I would have to come in for a second interview. He said I'll be meeting with his boss and the task lead who would be between him and me. I'm apprehensive about this, as I sense that since his superiors know that he and I are acquaintances, they don't trust his judgement in choosing me for this slot.
How can I best prepare for this interview? Should I try to quickly study up on the technical area I'm unfamiliar with? Should I just relax and let whatever will happen, happen? Should I ask him if there is anything I should know about the organization's background and political environment?