The article discusses ecclesiological issues that were included in the agenda of Pan-Orthodox Council but found no solution in the pre-conciliar debates: the Orthodox Diaspora; proclamation of autocephaly; the role of the Diptychs. The author then examines the issue of primacy in the Universal Church. All these questions can be combined and connected with the issue of the supreme or sovereign power in the Orthodox Church: its localization and mechanics for the implementation. The author examines content and essence of each issue, main approaches to their solution and attempts to reconcile them within the framework of the pre-conciliar discussions. The analysis reveals two ecclesiological models of the Orthodox Church structure and two approaches to understanding the sovereign power. These two models can be described by formulas: “first without equal” and “equal without the first”. The first model confers supreme power on Ecumenical Patriarch who is the “first in honor.” The second one insists on the fundamental equality of the autocephalous local churches and regards them as ecclesial sovereigns. The incompatibility of these models is the main cause of failure of all attempts to solve controversial issues within the pre-conciliar process.