Rivalries are born in sports in a variety of ways: geographic proximity, heated postseason series, illegal substances on gloves...
In case you missed what happened last night between the Washington Nationals and Tampa Bay Rays, here's the gist of it: Rays reliever/former Nat (the latter is important) Joel Peralta was ejected in the eighth inning of the Rays' eventual 5-4 win because of a foreign substance -- pine tar -- on his glove.
Now, according to Tampa Bay manager Joe Maddon, the Nats knew about Peralta's tendency to put pine tar on his glove while he was a member of the organization in 2010 and used that inside information to their advantage. As you can see from the video above, Maddon was not too thrilled.
Meanwhile, the Rays were tested a Nationals player in response, so Maddon chose reliever Ryan Mattheus -- to no avail.
There are two games left in this series, so the chances for some on-field fireworks are still good. Either that, or they can wait a few years until the next time they meet again.
I vote fireworks.