Marcelo Bielsa "Loco Bielsa" mural

Marcelo Alberto Bielsa Caldera (nicknamed Loco Bielsa, born 21 July 1955) is an Argentine association football coach and former defender, born in Rosario, Santa Fe. He is considered one of the most innovative coaches in the modern era and is the current manager of the Spanish First Division side Athletic Bilbao. Bielsa has managed not only football clubs but also the national teams of Argentina and Chile. In the latter country he achieved cult status due to the improved results of the national team under his leadership. His personality and gestures have in Chile captured the attention of media and unleashed a series of minor controversies both in the area of sports and in politics.