When the Argentinian succeeded Gregorio Manzano as boss of Los Colchoneros on 23 December 2011, the club from the Spanish capital were at something of a low ebb.
A home defeat to Real Betis had left them languishing 10th in La Liga, with around half the number of points amassed by the-then dominant pair of Real Madrid and Barcelona.
Fast-forward almost exactly 10 years, though, and Simeone presides over the Spanish champions. He can count not one, but two, La Liga titles from his spell in charge, as well as two Europa League triumphs and a couple of Champions League final appearances, with Atleti so cruelly denied by city rivals Real in Lisbon back in 2014.