Ronaldo, who joined Corinthians in a shock move last month, is still struggling to regain match fitness after recovering from a long-term knee injury he suffered last February.
The 32-year-old, who previously played for AC Milan and is determined to resurrect his career which has been in freefall since the 2006 World Cup, has not yet set a date for his debut.
"It's best not to make a prediction," he said at the weekend. "I don't want to go onto the pitch overweight with different strength in each leg. I have to be 100 percent ready."
"The improvement has been very good in the last 15 days and in a short time I will be on the pitch, where I belong," he added.
Ronaldo has not played domestic football in his homeland since he left as a 17-year-old in 1994 to join Dutch club PSV Eindhoven.
Corinthians kick off on Thursday with a home fixture against Barueri in the Paulista (Sao Paulo state) championship, one of the plethora of regional competitions which serve as a warm-up for the national championship.
Once he is fit, Ronaldo's presence could galvanise the Brazilian game which is sadly devoid of big names.
Unable to match the wages paid in Europe, Brazil has turned into an exporter of players who find even the less fashionable leagues of the Middle East and Eastern Europe more enticing than their homeland.
LUCKY ENOUGH
Those who remain fall into three categories; the youngsters who have yet to be sold abroad, veterans in their mid 30s returning for a final fling and the journeymen who are not good enough or lucky enough to earn a move.
Ronaldo is one of the younger of some former Brazilian World Cup players who are will be playing the Paulista and Carioca (Rio de Janeiro state) tournaments.
Former Barcelona midfielder Giovanni, 37, and ex-Werder Bremen defender Junior Baiano, 39, who both played in Brazil's 1998 World Cup team, will be appearing for unfashionable Mogi Mirim and Volta Redonda respectively.
Marcos, goalkeeper in Brazil's 2002 World Cup winning team will play for Palmeiras at the age of 35 while Viola, a striker in the 1994 squad, will turn out for modest Resende at the age of 40.
Palmeiras are away to Santo Andre on Wednesday in the Paulista championship, the same day that Brazilian champions Sao Paulo host Ituano at the Morumbi.
The state competitions, which date back to the days before air travel was commonplace, remain a controversial part of the Brazilian season.
Critics say they are outdated, uncompetitive and turn the season into an unrelenting marathon.
The teams in the Paulista tournament will have played up to 23 games even before they embark on the 38-match Brazilian championship campaign in May.
Leading clubs such as Sao Paulo also take part in the South American Libertadores Cup - up to 14 matches with huge distances to be travelled -- or the Copa Brasil knockout tournament.
