The onset of floods caught many residents off guard, particularly those living along the riverbanks.
Zagallo, who played alongside Pele in Brazil's 1958 and 1962 World Cup-winning teams, died Friday night of multiple organ failure at the Barra D'Or hospital in Rio after suffering a series of health problems in recent months.
Diniz presided over just two wins in his six months coaching Brazil, and had racked up a humiliating three straight losses in World Cup qualifiers, including at home to arch-rivals Argentina in November.
The six surviving children of the man widely considered the greatest footballer in history will hold a virtual meeting to mark the moment as several live in the United States, while a ceremony is scheduled to be held at the mausoleum in Santos that was opened to the public in May.
Brazil suffered a nightmare 2-0 defeat in Montevideo, crashing to a first loss against Uruguay in 22 years.