I'm sure you circled the Heat game on the calendar, but they sure as [expletive] aren't a rivalry. Maybe. I don't really know if the Bulls have a rivalry at all right now, but the Heat are probably the closest thing. It doesn't seem like the NBA really has many true rivalries anymore. I kind of think NBA rivalries are built throughout the course of a season or seasons. There aren't any Bears/Packers or Cubs/Cards traditional type rivalries. And the rivalries are pretty much between teams who are strong candidate for the title over the course of a few seasons. Considering the Bulls just got on the contender scene (and heck so did the Heat) rivalries are just beginning to begin with each other. I think both Heat and Bulls are more rivals with the Celtics because the Celtics are the team who's been at the top the longest and both teams have some history with this incarnation of the Celtics (LeBron while he was with the Cavs/and the beat them last year) and the Bulls with their tough series from a few years ago. On the Celtics end, they are an aging team trying to keep pace with the two younger, and what looks like better teams so they have some fuel on their end.