Menotti recovering after lung surgery
The source, who asked not to be named, said it was not an urgent operation but rather planned surgery to remove a small growth on the 72-year-old's right lung.
Menotti, a heavy smoker, was out of intensive care but still in hospital recovering.
Media reports said players who have played under Menotti sent him get-well messages, including Atletico Madrid striker Sergio Aguero, who was at Independiente with Menotti in 2005, and the retired former Argentina captain Roberto Ayala.
Menotti has been out of work since leaving his job as sporting director of Independiente in September along with the coach he had appointed, Daniel Garnero.
The lanky, long-haired Menotti, known as El Flaco (the thin one), played in midfield for Rosario Central, Racing Club, Boca Juniors, Santos of Brazil and Argentina in the 1960s.
Having steered Huracan to their only Argentine league title in 1973, he took charge of Argentina towards the end of the following year and coached them to their first World Cup title on home soil in 1978.
He became part of a bitter rivalry between two schools of thought in Argentine football, his attacking philosophy going up against the more cautious approach of Carlos Bilardo, who steered Argentina to their second World Cup, with Diego Maradona as captain, in Mexico in 1986.
Among the many clubs Menotti has coached are Barcelona, Sampdoria, Atletico Madrid, Boca, River Plate, Penarol of Uruguay and Mexico's national team.