Nana Akosah-Bempah scored the only goal of the game to hand the Citizens a 1-0 win away to Sundowns on Tuesday evening.
The victory has move City up to second in the Absa Premiership standings and McCarthy was delighted with the display on the night.
"I have to give credit to my boys for not going into the game already thinking about the holiday. They went out there and they were brave. We knew we were going to have our backs against the wall because Sundowns is a fantastic footballing team," McCarthy told SuperSport TV.
"We frustrated them in the areas we wanted. They knew what the game plan was and it worked to the tee. We could have had more than one if we had taken our chances but you can't fault the effort. I have to commend the Sundowns fans for what I'm seeing here. What a spectacle of South African football. Now I can happily say a happy Christmas for what we're seeing here today, to them and all the South African fans.
"We had a pressing zone where we came out not to allow Hlompho Kekana and [Tiyani] Mabunda to get on the ball as easily and be able to pick out those passes. The whole team really worked hard for each other. I think we are the deserved winners of the three points inasmuch as Sundowns had the possession. I think we were in control, they didn't hurt us in places they could have punished us so I'm very happy with the performance."