"I simply feel older," Bielsa said on Tuesday when asked how his experience of the 2002 and 2010 World Cups compared. "Time passes, eight years, and that tends to worsen your character and your health. I'm certainly worse than I was.
"But eight years have passed and the experiences aren't comparable."
Bielsa was in charge when Argentina failed to make it past the first round of the World Cup in Japan and South Korea. He quit the job in 2004 and went into retirement on his farm outside his home city of Rosario to study his vast collection of football videos, according to reports.
But Bielsa came out of retirement in 2007 to rejuvenate Chile and guide them to their first World Cup for 12 years. He is idolised by fans in Chile and has even won back the respect of Argentine fans who vilified him after the 2002 debacle.
Bielsa, one of the great eccentrics of Latin American football, often seems more at home in the relative backwater of Chile than he does in the soccer hot-house of Buenos Aires, but he said his heart still lay in the country of his birth.
"I feel nostalgia for Argentina, I always feel it," he said. "I'm Argentine and I belong to my country."
Bielsa's Chile play their Group H World Cup opener against Honduras on Wednesday.
