How to automatically populate /node/add/ form fields via simple logic? I have created a content type and the form looks like this:

Home team: Reds
Away team: Blues
Batted first: Reds
Batted second:
Fielded first:
Fielded second:

If Reds batted first, I know the Blues batted second, fielded first and that the Reds fielded second. How can I get Drupal (7) to populate these fields automatically via some simple logic?

I'm thinking the Computed Field module, but the values are not in the database yet: the form hasn't been submitted. So, I'm not sure I can access the Batted first value. Perhaps only via the &amp;$form_state array? - but can the Computed Field module access this array?

Anyway, how can I acheive this? Any suggestions are welcome. Thanks.
Module Conditional Fields does the job. 

It lets you assing values, visibility etc. of fields depending on other fields in the same form.

https://www.drupal.org/project/conditional_fields