The former Blackburn and Porto striker bagged two goals as the Buccaneers recorded a tightly contested 3-2 victory over Amakhosi at the FNB Stadium on Saturday, lifting Pirates above their Soweto rivals in the PSL standings.
And McCarthy, who joined the Sea Robbers as a free agent at the beginning of the campaign, says even his love for Chiefs could not detract from his commitment to Bucs.
"Growing up I was a Kaizer Chiefs supporter, so one would tend to work extra hard when playing against a team he used to support. But I am an Orlando Pirates player and it is my duty to play to the best of my potential," he said after the Soccer City spectacular.
"Credit must go to Kaizer Chiefs for their great attempt to draw level with us, they are a very great team to watch and it is a pity there had to be only one winner on the day."
Meanwhile, Pirates caretaker coach Augusto Palacios feels his side's performance was a reflection of the lessons they learnt in the 3-0 defeat to Santos last week, and he is hoping they can continue to grow in the build-up to Tuesday's clash against PSL leaders Mamelodi Sundowns.
He said: "I don't like losing games, but I cannot win or predict scores.
"We have learnt from our defeat against Santos and although we only had one day to prepare for this match we only have one day to prepare against Sundowns."