It's a job interview, and not a competition…

It’s easy to forget the real reason behind an interview – sometimes we want the job so much that chasing it becomes an all consuming competition where the prize is the job itself… something we can tell our family, our friends, and our ‘to-be-ex-colleagues’ about with pride in our voice. 
We compete, show our best side and best version of ourselves, learn all the answers for all the possible questions we may get, to outwit the rest.
We sidestep asking the right questions (I want the prize regardless), and get so emotionally blinded (I really, really want that job) that we even forget to make a realistic assessment of the guy at the other side of the table: our future boss…

To combat ‘competition fever’, here is a great article from Suzanne Lucas to get you focus on the important stuff again:
It's a Job Interview, Not a Beauty Pageant | Personal Success | BNET