Chiefs have won three games in a row since Middendorp replaced the sacked Giovanni Solinas at Naturena.
The Glamour Boys will look for more of the same when they host Absa Premiership champions Mamelodi Sundowns at FNB Stadium on Saturday (15h30).
Middendorp's side are sixth on the standings with 21 points from 15 games - a point behind the Brazilians, who have three matches in hand.
“We have won three games since Ernst Middendorp took over as the head coach,” Cardoso told his club's website.
“Those wins have given our supporters confidence and a positive holiday season.
“I urge our supporters to be our 12th man against Sundowns. They are the ones that give us our drive.”
He added: “Middendorp has brought in a lot of positive energy.
“He motivates us to give it our all. That’s also why we feel positive about the Sundowns match. We will be ready.”
Cardoso considers the fixture with Downs to be one of the biggest matches on the footballing calendar.
“After the Soweto Derby, this match has become one of the biggest games of the season,” Cardoso said.
“It will be tough. We will both be coming back from a break, so it will be interesting to see who reacts best to that.”
Cardoso featured in Chiefs' 3-0 CAF Confederation Cup win over Madagascar's Elgeco Plus on December 22 before the festive break as one of three centre-backs, along with Mario Booysen and Teenage Hadebe, in a 3-5-2 formation.