Little did Riyadh know that the most severe strategic blow to its regional influence would come not from Tehran, or Tehran's agents in Baghdad – but Cairo, its closest Arab friend. The ousting of Mubarak did not only mean the loss of a strong ally, but the collapse of the old balance of power. The region could no longer be divided on a Riyadh-Cairo v Tehran-Damascus axis. Revolutions have struck in both camps: in "moderate" Egypt and Tunisia, as in "hardline" Damascus and Tripoli. The principal challenge for the Saudi regime is no longer the influence of Syria, Iran or Hezbollah, but the contagion of revolutions.