Intense rivalries are a natural phenomenon. The most famous matchup was the Crispa-Toyota rivalry of the 1970s. Fans faithfully supported their favorite squads, and appeared in the multitudes at the Araneta Coliseum, or wherever the archrivals had met. In those days, the players were very passionate. On one occasion, they engaged in a major brawl. Players from both clubs were arrested and detained for one night in jail.

Other famous contests include:

* Crispa vs Great Taste
* Ginebra vs Purefoods (late-1980s rivalry, both are now sister teams)
* Añejo/Ginebra vs Shell (early-1990s rivalry)
* Purefoods vs San Miguel Beer (1990s All-Filipino Conference rivalry)
* Añejo vs San Miguel Beer (late-1980s rivalry)
* Ginebra/Gordon's Gin vs Alaska (late-1990s rivalry)
* Ginebra vs Red Bull (current rivalry as both teams met numerous times in the playoffs)
* Purefoods vs Red Bull (2005-06, both teams met twice in the Finals)
* Talk n' Text/Mobiline vs. Ginebra (perhaps the most watched match-up in 2004 and 2005)

Source: Wikipedia