“Initially, after leaving England, I was going to go to play in the USA. I was training at Ajax Cape Town to stay fit. But because I had never seen a Soweto derby I went up to Johannesburg to watch the game and that was where I met Pirates chairman Irvin Khoza," McCarthy was quoted as saying by IOL.
"We had a chat and he persuaded me to sign for Pirates," he continued.
McCarthy had a point to prove to Chiefs football manager Bobby Motaung, who labelled him 'finished' after the player was released by the Hammers due to his weight issues.
“I guess what happened the night before was also important. I was at a restaurant and Bobby (Motaung) was at the same place," he revealed.
"Afterwards there were all the rumours that Chiefs were trying to sign me. But Bobby’s comments were that I was finished, I was past my best, that I was washed up and that I wasn’t a big fish anymore," the former FC Porto striker added.
McCarthy went on to play an important role in helping the Buccaneers win three major trophies during his two-year spell with the club, before retiring from professional football at the end of the 2012/13 season.
“So I always had that in the back of my head, which is why I was happy to sign for Pirates - to show Chiefs how washed up I was; I would show them what a big fish looked like," he said.
"I guess still now you can say that whenever I play against Chiefs, even as a coach, they know I will be out to try to hurt them," the Cape Town-born trainer indicated.
McCarthy will be looking to mastermind Chiefs' downfall when City host the Soweto giants in a Premier Soccer League (PSL) match at the Cape Town Stadium on Saturday.
However, the 40-year-old tactician remains a Chiefs fan as it is the club he grew up supporting while growing up in the Mother City.
“Overall, though, I still have a soft spot for Chiefs. It’s the club I loved as a child. Growing up, I supported Chiefs,'" McCarthy disclosed.
"My dad was a massive Chiefs fan and as kids, if we didn’t support Chiefs, well, then we would have to find another place to stay," he concluded.