City edged Mamelodi Sundowns 4-2 on penalties in the last-four after a 1-1 draw across two legs, while cup holders SuperSport ousted Kaizer Chiefs 3-2 on aggregate.
Matsatsantsa beat the Citizens 4-2 on penalties in last year's tournament decider at Moses Mabhida Stadium after 120 minutes of football produced a 1-1 stalemate in Durban.
However, McCarthy says the costal outfit have since discovered "the formula" to take down the Tshwane giants.
"It's gonna be a completely different game of football," said McCarthy, whose men defeated visiting United 2-0 on the opening day of the 2018/19 Absa Premiership season last month.
"We had them in the first game. I think we dominated. It was one of the best performances from my side.
"We've found a formula on how to beat them, but since they lost against us they have not lost any game. They have gained momentum.
"I think it's gonna be two awesome teams not afraid to lose. It's gonna be a good final irrespective of it being a repeat of last season," concluded Bafana Bafana's record scorer with 31 goals.
City, in seventh place on the table with five points from four games, will resume their league campaign after the FIFA break against Kaizer Chiefs at Cape Town Stadium on September 15.