I've only been competing for rank one in the past week and the times that I've held it (only once at actual reward time) I have fought a few battles with the 2/3/4 guys but have never lost.
I assume if I attack from #1 and lose I maintain the #1 spot but figure it's worth it to confirm that you don't lose your standing. I would actually like to auto-play these on occasion to get an idea of what the AI does when I'm not around. Mostly to confirm some assumptions I've been making based on squad play on what it does on the first turn.
Not that it's a big deal to drop but whenever you don't have to...