Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life.
Attacking a zombie token does not count as attacking the main creature in an encounter. The easiest way to figure out what happens in an encounter is to imagine that the player who attacked a zombie focused strength instead (or some similar non-interactive action). Thus, if Player A chooses Player B and Player B attacks a zombie, then Player A is hit by the lizard for 10.