The Boston Celtics are playing the Washington Wizards on tonight in the fourth and final meeting of the regular season between the two teams. It's also going to be a game that could go a long way towards deciding which team will emerge as the solid number 2 seed in the Eastern Conference.

According to ESPN.com, recent meetings between the Celtics and the Wizard have featured flagrant and hard fouls, post-game nose bops, a police presence and one where the Wizards were wearing an all-black funeral attire. With that in mind, here are some facts that will explain just how the Celtics and the Wizards have emerged as the NBA's most chippy and unexpected rivalry.

The dispute has a date to last season. In the teams' third meeting in January 2016, Celtics forward Jae Crowder - who many regards as the central protagonist in this entire rivalry drama - got tagged with a technical foul in the final minute of Boston's 119-117 victory in Washington.

During that moment, Crowder could be seen barking at the Wizards bench as well as pointing at then-Wizards coach Randy Wittman. After the game, Crowder accused Wittman of cursing at him and calling him soft. Crowder said that he felt like Wittman was getting away with a lot of curse words and some very inappropriate words to him, and he retaliated, which eventually got him the technical.

According to Chat Sports, Wittman later admitted that he indeed yelled at Crowder but denied that he was using profanity. There was no obvious escalation when the teams met again two weeks later - which was another lopsided Boston win - and Wittman was then fired after the season.

It was also reported that the Wizards and Celtics were also two of the primary suitors for center Al Horford when free agency opened in July. Boston ultimately won that tug-of-war, inking Horford to a four-year, $113 million contract.

Ever since then in the opening of the 2016-2017 season, both the Celtics and Wizards went back and forth in every game where both teams played each other. All their games this season featured a lot of drama and many analysts are now considering it to be one of the most heated rivalries this season that could potentially lead to the postseason if they ever are matched in a possible series.