Olympiacos CFP (Greek: ΟΣΦΠ - Ολυμπιακός Σύνδεσμος Φιλάθλων Πειραιώς - Olympiakos Syndesmos Filathlon Peiraios), Olympiacos Club of Fans of Piraeus, is a large and the most popular Greek multi-sport club based in Piraeus, Athens. The club is parent to 17 different competitive departments including football (Olympiacos F.C.), basketball (Olympiacos B.C.), volleyball (Olympiacos S.C.), water polo (Olympiacos Water Polo Club), athletics and swimming, amongst others, which have won numerous domestic and European titles over the club's history. Olympiacos has the record of winning the treble in two different team sports (basketball and water polo) while Olympiacos has won a Balkans Cup in football. In addition to this, in the total number of Olympiacos' athletes, Olympic winners and World Champions are included. Olympiacos CFP was founded on March 10, 1925, as a football club initially, when the members of the "Piraeus Football Club" and the "Piraeus Fan Club" decided, during a historical assembly, to dissolve the two clubs in order to establish a new unified one football club, with the young Olympic games winner boy as their emblem. Notis Kamberos announced the name Olympiacos and Michalis Manouskos completed it to its full name, Olympiacos Club of Fans of Piraeus. The Andrianopoulos brothers, however, were those who significantly raised the reputation of the club and added glory to it. Children of a prosperous family, they made the name of Olympiacos known over Greece. Yiannis, Dinos, Giorgos, and Vassilis were the first to play. Leonidas made his appearance later on, and played for a short time. The club's offensive line, made up of the five brothers, soon became legendary and, hence, Olympiacos is also known as Thrylos (Legend), after this classic side of the 1930s which won a hatful of titles.

Panathinaikos Athlitikos Omilos (Greek: Παναθηναϊκός Αθλητικός Όμιλος, listen (help·info)), widely known both as Panathinaikos or PAO, is a Greek multisport club based in Athens, Greece. Panathinaikos has been very successful throughout its history, as its teams and individual athletes have won numerous titles. In English, the club's name would be Pan-Athenian Athletic Club. According to the official history of the club, Panathinaikos was founded by George Kalafatis in 1908, when he and 40 other athletes decided to break away from Panellinios Gymnastikos Syllogos, following the club's refusal to form a football team.