Marcelo Alberto Bielsa Caldera (Spanish pronunciation: , nicknamed Loco Bielsa , English: Madman Bielsa; born 21 July 1955) is an Argentine football manager who was last in charge of Lille. Bielsa has managed football clubs and also the national teams of Argentina and Chile. In Chile, he achieved cult status due to the improved results of the national team under his leadership. His personality and gestures during his stint in Chile captured the attention of media and unleashed a series of minor controversies both in sports and politics. On 8 August 2015, Bielsa resigned as Marseille's coach.
In 1980, after retiring from playing in football, Bielsa decided to start a career as a football manager. His first job was coaching the youth divisions of Argentine club Newell's Old Boys. In 1990, he was given the task of managing Newell's first team, where he would later go on to win the 1990 Torneo Apertura and the 1990–91 Torneo Integración, defeating Boca Juniors on penalties. "El Loco" managed the squad that competed in the final of the 1992 Copa Libertadores, losing to São Paulo on penalties. Weeks later, after enduring defeat in the Copa Libertadores final, Bielsa and Newell's won the 1992 Torneo Clausura.