A 54th minute Peter Shalulile goal at Loftus Versfeld secured a 1-0 win for the Brazilians in their quarter-final first leg encounter.
Cardoso felt his team played well in patches, but explained there is still a long way to go to secure their passage to the semi-finals.
Reflecting on the match, the Brazilians boss told SABC Sport: "I think the first half we were not very clever in the way we had to play, because the things that we knew we had to put on the pitch we didn't.
"So, we ran away from the plan that we had defined that's important to do. When you do it it's obvious, you'll not play the game you want to play.
"We controlled the first half, but then I think in the second half we only did in the first 20 minutes what we needed to do. Out of that we got the goal, and at that moment I felt we played what we wanted to play.
"Then again, we did not have the best emotions and could have continued with the same style that we wanted to have in order to go for the second goal. But we also need to understand the game we were playing and what team we were playing," he added.
Cardoso continued: "The tie is at half-time, we have hard work ahead of us, but it's better to go with a 1-0 rather than a 1-1 or a 0-0.
"So, I'm not really excited but conscious about what is ahead and what we got."