I want to start a discussion about world volleyball rivalries. What I mean is to enumerate/discuss/try to remember or find out the greatest or local volleyball rivalries in each country. It could be between the two biggest/most successful clubs in the country or between some local teams which are known for their "hot" derbies. Also, I want to mention players who have switched sides in these rivalries.
I know volleyball is not related to football and that volleyball fans are far more peaceful and do not take these rivalries so seriously. We also know that players' wages are way lower and sometimes they have no choice but change clubs regardless of history. But still I would be interested to know more about the behaviour of players changing arch rivals just like that.