"It's interesting because it's different from anything I've taken part in during my international career," he told reporters.
"But I've played against South American teams before and played in the Copa America outside Brazil.
"I know how difficult it can be and that's why we have to prepare well and qualify as quickly as possible."
The 26-year-old Real Madrid striker was included in the Brazil squad which won the 1994 World Cup when he was 17, although he did play.
He then spearheaded the Brazil team which finished as runners-up at France '98 and was topscorer as the South Americans won their fifth world title last year.
But he has never experienced the tension of a South American qualifier.
Brazil qualified automatically for the 1998 World Cup as defending champions and Ronaldo missed the qualifiers for 2002 when he was plagued with his knee injuries.
Brazil struggled without their top player, using four coaches and losing six matches before finally clinching their place in Japan and South Korea with a 3-0 win over Venezuela in their last match.
This time, Brazil have to go through the qualifying even though they are defending champions after a change in the FIFA rules. They will play 18 matches between this weekend and November 2005.
"This game against Colombia is going to be very difficult," said Ronaldo.
"We have to forget everything that happened in the last qualifiers and give it everything we have this time."
He added: "I'm still ambitious even after so much success."
