The Citizens stunned a much-fancied Sundowns side 1-0 in the 2018 MTN8 semi-final first-leg match at the Cape Town Stadium in the Mother City.
“I’m very happy that we kept a clean-sheet. It’s not an easy game. Sundowns is the best team in our land. They’ve got the best players and make life difficult for you,” McCarthy told SuperSport TV.
Improving central defender Tariq Fielies scored the only goal of the match with 14 minutes left on the clock.
“When you have a game of this magnitude and you keep clean-sheet you have to praise your players," he continued.
"The effort the players gave, they gave everything. It was only a matter of time until that goal was going to come because we piled on the pressure,” McCarthy explained.
The Citizens are hoping to reach the final of the MTN8 for the second year running.
They lost 4-2 to SuperSport United on penalties following a 1-1 stalemate in a memorable final which was played at the Moses Mabhida Stadium.
McCarthy was happy with charges' never die spirit against the Brazilians, who are hoping to win the Top 8 Cup for the first time since cellular giants MTN began sponsoring the tournament in 2008.
"At one stage if anyone of us was to put the ball on target it was bound to go in because it was coming," the former Orlando Pirates striker said.
"I’m very happy for the boys because they persevered and never gave up," he added.
The second-leg encounter will be played at the Lucas Moripe Stadium in Tshwane next weekend. The winner on aggregate will take on Kaizer Chiefs or SuperSport in this year's final.