BuddyPress.org

I am trying to add a new rewrite for a group (e.g. groups/sports_tennis) and having trouble finding the proper query string for $rewrite portion of add_rewrite_rule().

Here is an example:

add_rewrite_rule( 'groups/sports-tennis', 'index.php?pagename=groups/sports_tennis', 'top' );

Obviously pagename does not work, but this is similar to what I need to accomplish.

How exactly are group rewrites handled and how can I view the group using a query string with the proper parameters?

Thanks in advance.