The Bluebirds go into the clash 1-0 behind following their defeat in the opening leg at Selhurst Park, but have won 13 of their 17 home games this term and will fancy their chances of turning the tables and securing a third visit to Wembley in five seasons.
Palace manager Dougie Freedman has attempted to pile the pressure on the Welsh club by suggesting their supporters will be "scared stiff" of seeing their charges come up short again following their play-off defeats to Reading in the semi-finals last year and Blackpool in the 2010 final, as well as their 2008 FA Cup final loss to Portsmouth.
Mackay says he is unconcerned by his fellow Scot's comments, and has backed the Cardiff faithful to be their 12th man.
Mackay told a press conference: "As far as his comments are concerned I look after my own club, it is not my style to about other clubs. I have enough to be dealing with here, but, needless to say, part of the team talk is done.
"We are obviously excited. We are in the semi-finals of a cup, we are preparing properly but we are looking to enjoy it.
"We have done well in the Carling Cup this season, we have had some fantastic games and have all enjoyed it.
"We are 1-0 down at half-time so to speak, but we are going back to our stadium and it will be a full house and rocking like it was on Saturday.
"I was delighted with how the fans showed their passion and got behind the team on Saturday and I don't any difference tomorrow [Tuesday] night. It will be a fantastic occasion but we need to play the game, not the occasion.
"The fans have been through it before but I can only talk about what I see and feel here, and I feel a confident stadium with people who desperately want the team to do well because they see the team care, they see a team playing with passion and they embrace that. That's why I feel they can be our 12th man back at Cardiff City Stadium."
With Cardiff flying high in the npower Championship and targeting promotion, Mackay played his strongest available side in Saturday's thrilling 3-2 victory over Portsmouth, which was sealed by Craig Conway's last-gasp strike.
Freedman, meanwhile, was able to rest the majority of his side, who lie firmly ensconced in mid-table.
But Mackay does not expect his side to suffer in comparison.
He said: "Everyone looks at their own situation and what their remit is, whether it is staying in the division, finishing in mid-table, the top 10, the top six or whatever it may be.
"But on Saturday I wanted to put a strong team out there, it was an important league game and we had to make sure it did not detract from this week.
"I have no doubt in the athleticism of my team to play Saturday and Tuesday like we have done in the league many times.
"If we had league games on Saturday and Tuesday I wouldn't rest nine players, I would play my team. We have a confidence in the ability of my team to run for 90-95 minutes or longer if it should be needed."
Mackay will wait before making a decision over the availability of Kevin McNaughton.
The Scot is currently recovering from the calf niggle that has kept him out of action since the first leg. Darcy Blake is set to continue in his place if he does not make it.
Striker Rudy Gestede is also coming back from an ankle problem, while Robert Earnshaw was named on the bench for Saturday's win over Portsmouth after a muscle strain.