Leao, who left his last club after brawling with reporters, took charge of Sao Paulo for the second time on Monday ahead of their quarter-final second leg match.
Sao Paulo won the first leg 1-0 with a goal by Brazil striker Luis Fabiano.
Leao, 62, replaced Adilson Batista who was sacked nine days ago with Sao Paulo in sixth place in the Brazilian championship having gone six games without a win.
"When you're hand-picked it's because the responsibility is greater," Leao told reporters after becoming the club's third coach of the year.
Leao had been out of work since leaving Goias in the relegation zone in 2010 after he and his players became involved in a brawl with radio reporters on the pitch at the end of a match.
The former goalkeeper, who played for Brazil at the 1974 and 1978 World Cup and coached his country from 2000-01, first took charge of Sao Paulo in 2004.
He steered them to the state championship in the first half of 2005 before leaving to coach in Japan.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.