McCarthy put Bucs ahead in the 24th minute on their way to a 2-1 win in the Telkom Knockout over 'Lidoda Duvha', but he then limped off the pitch six minutes later.
The Brazilian coach tells Football365.co.za that his hand was forced to pick McCarthy for the clash, despite the former Bafana Bafana ace struggling to regain full fitness as he battles with a hamstring strain.
"We expected to use him later in one or two weeks, but due to circumstances we had to use him. He got the injury after the game against Maritzburg United (August 24) and recently he's been training only part time but he has managed to play some games," Leal said.
"Against Black Leopards, the difference was that the speed of the game forced him to feel it again and now we will have to see what the doctor and the physiotherapist say. I think he will stay a few days without playing, without practicing," he continued.
Leal has bemoaned McCarthy's injury woes saying the only South African player to win the UEFA Champions League has plenty to offer.
He said: "He is really a different player that gives us not only the confidence but the capacity to hold the ball, to wait for the midfielders and the wing backs to arrive.
"He is a very smart player with experience and I think he is really an outstanding player but he has not been able to perform as much as he is capable because of the fitness level after the injuries. If he recovers completely and gets in the best possible shape he will be amazing," Leal added.