The Brazilians suffered a 3-2 defeat to TS Galaxy on Tuesday to all but hand the Betway Premiership title to rivals Orlando Pirates.
The Buccaneers can claim their first top-flight title since the 2011/12 season with victory over Durban City in their penultimate clash this weekend.
They complete their campaign away to struggling Orbit College next weekend.
Sundowns, meanwhile, turn their attentions to Moroccan side AS FAR, who they face over two legs.
Cardoso's team made it to the final last year but lost out to Egyptian top-flight team Pyramids.
"It's now time to get the energy as soon as possible for the weekend. The boys are surely going to show another proof of character," said the Brazilians boss on IOL.
"We'll try to recover them as much as possible so that they can produce a good match in this Champions League final."
Reflecting on their domestic season, a downbeat Cardoso added: "With the number of points that we have, in the last five years we would have been champions.
"Now, we just have to wait and see what's going to happen in the games that are still to be played by Pirates.
“It's not that we had a bad season. If someone else becomes the champion, it simply means they had a better season.”
Teboho Mokoena’s stunning first-half strike proved decisive as Mamelodi Sundowns secured a 2-1 aggregate victory over AS FAR to win the CAF Champions League in Morocco on Sunday night.
Mamelodi Sundowns defender Divine Lunga has been officially released from Zimbabwe’s Unity Cup squad in order to focus on the CAF Champions League final second leg.
Aubrey Modiba says Mamelodi Sundowns still believe in their chances of claiming a ninth successive Betway Premiership title.
Mamelodi Sundowns are on their way to their CAF Champions League final second leg a day late after a delay in receiving a permit from Moroccan authorities to land in Rabat.
