One of the best "forgotten" NBA rivalries of all time involved the bloodbaths between the New York Knicks and Miami Heat in the late 1990s. Between Pat Riley leaving the Knicks for the Heat and the explosive personalities on both sides, these two made for TV gold when they met in the playoffs in four straight seasons between 1997 and 2000. Tensions really came to an all-time high in 1998, when New York's Larry Johnson and Miami's Alonzo Mourning came to blows near the end of Game 4 of the Eastern Conference Semis. Knicks head coach Jeff Van Gundy famously grabbed onto Mourning's legs to try and stop the melee.
All Van Gundy got for his efforts was a legitimate trampling.
Unfortunately, he was unsuccessful. Mourning and Johnson, who have legitimate bad blood and seething distaste for one another dating back to their days with the Charlotte Hornets, both landed a few punches.
Both Mourning and Johnson were suspended for Game 5, and the Knicks actually ended up winning the series before Reggie Miller broke their hearts once again in the next round.
One thing that nostalgia-blind NBA fans are totally correct in asserting is the fact that there is less genuine beef and hatred between players nowadays. Johnson and Mourning hated each other, and that bad blood gave us one of the most memorable brawls in NBA history.