Ronaldo headed two goals in seven minutes in the first half as Corinthians beat Sport 4-3 to improve to sixth in the Brazilian championship on Thursday.
"I don't remember having done that before. Some incredible things are happening," Ronaldo told reporters.
Ronaldo, who equalised in the 28th minute following Fabiano's opener for Sport and put Corinthians ahead in the 35th, took his tally to 16 goals in 24 matches since coming back in March after knee surgery as an AC Milan player last year.
Midfielder Cristian hit Corinthians' third early in the second half but Sport's Vandinho struck twice in five minutes to level before substitute Moradei drove home the winner from outside the box 10 minutes from time.
Atletico Mineiro added to Sao Paulo's woes by beating them 2-0 at home to go a point above Internacional, 4-2 winners at home to Fluminense on Wednesday, at the top of the standings with 24 points from 11 matches.
Title holders Sao Paulo, champions from 2006 to 2008, are 15th after only two wins.
"We've reached the limit, it can't get worse than this. We have to react because things are bad ... It's embarrassing for Sao Paulo," said Brazil midfielder Hernanes, the team's ex-captain now confined to the bench.
