In his book on European reactions to regime change in Napoleonic France, Richard Rosecrance wrote that, after war, regime change is the most alarming event for state system with the potential of provoking radical reactions form neighbouring states. But, what if the political elite of the new regime is ideologically compatible, at least theoretically, with the ruling regimes in neighbouring regional powers? Saudi Arabia has expressed its hostility towards the overthrow of Mubarak since the beginning of the Egyptian uprising. Since the early 1980s, Riyadh and Egypt have built an axis that weighed on regional affairs. Yet, one may argue that the fall of Mubarak haven’t stripped Riyadh of its leverage in relations with Cairo. Saudi Arabia could gain momentum with the empowerment of political Islam in Egypt. This may indeed be the case if we add the dire need for Saudi financial assistance and the perseverance of key elements from Egypt’s old regime. In addition, the political empowerment of Islamists in Egypt may comfort the Saudi regime’s legitimacy at home. However, the paper argues that the toppling of Mubarak is rather a double-edged change for Saudi Arabia, especially if put within the wider matrix of regional international relations. The impact of Egypt’s new Islamist political elite on relations with Saudi Arabia is disputed by many factors among which: the complex history of Saudi Arabia’s transnational relations with Egyptian Islamist movements, Saudi-Egyptian historical regional powers rivalry, Egyptian authorities’ current crackdown on foreign funding to NGOs, the delay of Saudi Arabia’s financial assistance to Egypt, part of public opinion’s mounting hostility towards Saudi Arabia’s stance from the revolution, in addition to Egypt’s positions on regional files especially Iran, Qatar’s rising star, Palestine and the “Arab Spring”. This paper builds upon an in-depth study of Egyptian-Saudi relations in the framework of a PhD dissertation. The suggested outline includes a review of bilateral state relations before and after the revolution. It then explores Saudi Arabia’s relations with various Islamist movements in Egypt. The paper has two main contributions: (1) to examine how state relations on the official level interact with transnational flows between these two regional powers; (2) to explore the potential of a new Egyptian-Saudi rivalry based on the same reference, Islamism.