The Derby of the Eternal Rivals (Greek: Ντέρμπι των αιωνίων αντιπάλων), also called Mother of All Battles (Greek: Μητέρα των μαχών), is the name of the basketball local derby in Attica (Piraeus and Athens) between Olympiacos and Panathinaikos.

The Greek powerhouses have won a combined ten EuroLeague titles since 1996, thus being among the most successful clubs in European basketball history.

[1][2][3][4][5] The rivalry between the two top Greek clubs can be traced back to some social, cultural and regional differences.

However, this kind of clash was much more pronounced in the past, as the class differences between the fanbases have faded out and the social gap that once separated the two sides has closed over the years.

Their rivalry is highly credited, especially in the 1990s-2000s, when they met each other in several regular season and playoff series, and in some EuroLeague matches which marked their history.

season 67–53, Playoff 53–45) 1 Panathinaikos won the Greek Cup semifinal (20–0), after Olympiacos decided to forfeit the game in protest at refereeing decisions.