Corinthians held at home in season opener
Striker Pedrao put the visitors ahead in the 22nd minute with the Corinthians defence appealing in vain for offside and added the second by converting a penalty just after the hour.
Chicao pulled one back from a controversial penalty in the 83rd minute and Jorge Henrique levelled with two minutes to play as Corinthians narrowly avoided a shock defeat in their first game of the 2009 season.
Ronaldo, who signed for Corinthians last month, is still trying to regain match fitness after suffering a serious knee injury while playing for AC Milan last February.
The 32-year-old is expected to make his debut in about one month's time.
The Paulista is the largest of the regional tournaments that serve as a prelude to the Brazilian championship.