Tennis players ... any circumstances cross is the one where the court ends and the seats begin. Lest we forget, this year’s Australian Open has reminded us of those unwritten rules.

Welcome back to the Monday Tennis Briefing, where The Athletic will explain the stories behind the stories from the past week on court. This week, the Australian Open came to a close in Melbourne.

Now it's time for ball boys and ball girls to take center court in a reality-style documentary. Tennis Australia this week said “Ballkids,” a 65-minute film, is set to “lift the lid on the unsung ...