Brayan Leon scored the only goal of the game at the Stade Hammadi Agrebi on Sunday with his powerful header after 51 minutes.
Sundowns dominated large chunks of the game but were under pressure from their hosts, especially in the first half where Florian Danho crashed a shot off the frame of the goal.
As they prepare for the second leg at Loftus Versfeld, Cardoso says the mentality of his players must be strong if they are to secure their place in the final for the second season in a row.
Looking ahead to Saturday's clash, the Brazilians boss said in the Citizen: "We don't take anything for granted. The attitude in Pretoria must be even stronger, show more commitment and tactical discipline.
"We need to have more control of the match and play to win because we don't play to win, then you can suffer. The team did well and understood different moments of the game."
Sundowns were losing finalists to Egyptian side Pyramids FC last season.
Reflecting on the narrow win over Esperance, Cardoso added: "As expected, we had different moments in the game and that's how it will be in Pretoria and the team that deals better with different moments will progress to the final."
Sundowns will be without Grant Kekana for the second leg after his red card, but Aubrey Modiba makes a return after serving a recent suspension.
"Regarding who is in and who will be out? Let's return to Johannesburg and understand how we want to play this game and what we must do. What we know is that we are at half-time and how important the second match is," Cardoso added.
