Recep Tayyip Erdogan's famed mantra "whoever wins Istanbul wins Turkey" rings very loud after the country's president forced a rerun of the March 31 municipal elections and lost. We break down the vote in the city where Erdogan served as mayor a quarter-century ago and ask if it's a turning point for a nation that has seen more and more power concentrated in the hands of one man. The win makes new mayor Ekrem Imamoglu of the centre-left CHP an instant factor to reckon with in Turkish politics.